Heterogeneous polymer blend with continuous elastomeric phase and process of making the same

ABSTRACT

A heterogeneous polymer blend comprises a dispersed phase comprising a thermoplastic first polymer having a crystallinity of at least 30% and a continuous phase comprising a second polymer different from the first polymer. The second polymer has a crystallinity of less than 20% and is at least partially cross-linked.

PRIORITY CLAIM

This application claims the benefit of U.S. Provisional PatentApplication No. 60/693,030, filed on Jun. 22, 2005.

FIELD

This invention relates to a thermo-processable heterogeneous polymerblend, and to an in-reactor process of making such a polymer blend.

BACKGROUND

Heterogeneous polymer blends comprising a second polymer dispersed in amatrix of a first polymer are well-known and, depending on theproperties and the relative amounts of the first and second polymers, awide variety of such polymer blends can be produced. Of particularinterest are polymer blends, also referred to as thermoplasticelastomers, in which the first polymer is a thermoplastic material, suchas polypropylene, and the second polymer is an elastomeric material,such as an ethylene-propylene elastomer or an ethylene-propylene-diene(EPDM) rubber. Examples of such thermoplastic elastomers includepolypropylene impact copolymers, thermoplastic olefins and thermoplasticvulcanizates.

Unlike conventional vulcanized rubbers, thermoplastic elastomers can beprocessed and recycled like thermoplastic materials, yet have propertiesand performance similar to that of vulcanized rubber at servicetemperatures. For this reason, thermoplastic elastomers are useful formaking a variety of articles such as weather seals, hoses, belts,gaskets, moldings, boots, elastic fibers and like articles. They arealso particularly useful for making articles by blow molding, extrusion,injection molding, thermo-forming, elasto-welding and compressionmolding techniques. In addition, thermoplastic elastomers are often usedfor making vehicle parts, such as but not limited to, weather seals,brake parts including, but not limited to cups, coupling disks,diaphragm cups, boots such as constant velocity joints and rack andpinion joints, tubing, sealing gaskets, parts of hydraulically orpneumatically operated apparatus, o-rings, pistons, valves, valve seats,and valve guides.

One method of making the aforementioned polymer blends is by mixing twodifferent polymers after they have been polymerized to achieve a targetset of properties. However, this method is relatively expensive makingit much more desirable to make blends by direct polymerization. Blendingby direct polymerization is well known in the prior art and typicallyuses multiple reactors in series, where the product from one reactor isfed to a second reactor having a different polymerizing environment,resulting in a final product that is an intimate mix of two differentproducts. Examples of such processes employing vanadium catalysts inseries reactor operation to produce different types of EPDM compositionsare disclosed in U.S. Pat. Nos. 3,629,212, 4,016,342, and 4,306,041.

U.S. Pat. No. 6,245,856 discloses a thermoplastic olefin compositioncomprising polypropylene, an ethylene-alpha olefin elastomer and acompatabilizer comprising an ethylene-propylene copolymer having apropylene content of greater than 80 weight percent. According to thispatent, the individual components of the composition can be separatelymanufactured and mechanically blended together in a mechanical mixer ortwo or more of the components can be prepared as a reactor blend using aseries of reactors where each component is prepared in a separatereactor and the reactant is then transferred to another reactor where asecond component is prepared. In the absence of the compatabilizer, theelastomer phase is said to be uneven with particles >5 microns, whereasthe addition of the compatabilizer is said to improve dispersion suchthat the elastomer phase has a particle size of about 1 micron. Theelastomer phase of this polymer blend is not cross-linked.

U.S. Pat. No. 6,207,756 describes a process for producing a blend of acontinuous phase of a semi-crystalline plastic, such as polypropylene,and a discontinuous phase of an amorphous elastomer, such as aterpolymer of ethylene, a C₃-C₂₀ alpha olefin and a non-conjugateddiene. The blends are produced in series reactors by producing a firstpolymer component in a first reactor, directing the effluent to a secondreactor and producing the second polymer component in solution in thesecond reactor in the presence of the first polymeric component. U.S.Pat. No. 6,319,998 also discloses using series solution polymerizationsto produce blends of ethylene copolymers. U.S. Pat. No. 6,770,714discloses the use of parallel polymerizations to produce differentpolymeric components that are then blended through extrusion or usingother conventional mixing equipment. One polymeric component is apropylene homopolymer or copolymer and the second polymeric component isan ethylene copolymer.

One particularly useful form of thermoplastic elastomer is athermoplastic vulcanizate (“TPV”), which comprises a thermoplastic resinmatrix, such as polypropylene, within which are dispersed particles of acured elastomeric material, such as an EPDM rubber. TPVs are normallyproduced by a process of “dynamic vulcanization”, which is a process ofvulcanizing or cross-linking the elastomeric component during intimatemelt mixing with the thermoplastic resin, together with plasticizers(e.g. process oils), fillers, stabilizers, and a cross-linking system,under high shear and above the melting point of the thermoplastic. Themixing is typically done in a twin-screw extruder, to create a finedispersion of the elastomeric material within the thermoplastic resinwhile the elastomeric material is cured. The levels of thermoplasticresin and plasticizer (oil) can be adjusted to produce grades havingdifferent profiles of hardness, rheology and engineering properties,although in general it is difficult to produce TPVs by dynamicvulcanization in which the content of the elastomeric phase is greaterthan 50wt % of the overall polymer blend. Examples of dynamicvulcanization are described in the U.S. Pat. Nos. 4,130,535 and4,311,628.

However, while dynamic vulcanization is effective in producing TPVs witha unique profile of properties, it is expensive and suffers from anumber of disadvantages. Thus the production of quality product istechnically challenging and specialized equipment is needed. Moreover,the process involves many steps, each one critical to the eventualquality of the final product. Forming the polymer blend normallyinvolves separately comminuting bales of the elastomeric polymer (whichis typically how EPDM rubber is commercially distributed), mechanicallymixing it with the thermoplastic resin along with the processing oils,curatives, and other ingredients in a suitable high shear mixing deviceto comminute the rubber particles and cure them to generate cured rubberparticles embedded in a continuous thermoplastic resin matrix. The curedrubber particles in the finished products have an averaged particle sizeof 1 to 10 micron. Careful injection of processing oil helps manage therheological characteristics of the fluid in the reactive extruder (tominimize pressure buildup) as well as product properties such ashardness. Precise control over the size and distribution of thecross-linked elastomer particles is critical, as it affects propertiessuch as elastic recovery (as measured through compression set). Whilethe products produced with existing technology have many desirableproperties, there are gaps in the overall properties profile. Some ofthese are the need for higher service temperatures, improved elasticrecovery, softer products, higher tensile strength, easierprocessability, oil-free compositions, and colorless products.

An improved process for producing TPVs is disclosed in U.S. Pat. No.6,388,016, incorporated herein in its entirety, in which a polymer blendis produced by solution polymerization in series reactors employingmetallocene catalysts and the resultant blend is subjected to dynamicvulcanization. In particular, the process involves feeding a first setof monomers selected from ethylene and higher alpha-olefins, and asolvent, to a first continuous flow stirred tank reactor, adding ametallocene catalyst to the first reactor in an amount of 50 to 100weight % of the total amount of catalyst added to all reactors,operating the first reactor to polymerize the monomers to produce aneffluent containing a first polymer, feeding the effluent from the firstreactor to a second continuous flow stirred tank reactor, feeding asecond set of monomers selected from ethylene, higher alpha-olefins andnon-conjugated dienes, and optionally additional solvent, to the secondreactor, operating the second reactor to polymerize the second monomersto produce a second polymer containing diene, recovering the resultingfirst and second polymers and blending them with a curing agent underconditions of heat and shear sufficient to cause the blend to flow andto at least partially crosslink the diene-containing polymer and form adispersion of cured diene-containing particles in a matrix of the firstpolymer. It will, however, be seen that this improved process stillrelies on dynamic vulcanization to cure the elastomeric component. As aresult the cured diene-containing particles have an average particlesize in the range of 1 to 10 microns.

An in-reactor process for producing cross-linked polymer blends, such asTPVs, is disclosed in our co-pending U.S. patent application Ser. No.60/693,030, (Attorney Docket No. 2005B067), filed on Jun. 22, 2005. Inthis process, at least one first monomer is polymerized to produce athermoplastic first polymer; and then at least part of the first polymeris contacted with at least one second monomer and at least one polyeneunder conditions sufficient to produce and simultaneously cross-link asecond polymer as a dispersed phase within a continuous phase of thefirst polymer. In the resultant polymer blend, the thermoplastic firstpolymer has a crystallinity of at least 30% and the dispersed phasecomprises particles of the second polymer having an average size of lessthan 1 micron, wherein the second polymer has a crystallinity of lessthan 20% and is at least partially cross-linked. In this way, the needfor a separate dynamic vulcanization step to cross-link the secondpolymer is avoided.

All of the heterogeneous polymer blends described above have athermoplastic continuous phase with discrete domains of an elastomericphase dispersed in the thermoplastic matrix. To retain the continuousthermoplastic phase in such blends, it is necessary to ensure that theamount of thermoplastic material present in the blends is reasonablyhigh. However, a high content of thermoplastic material leads toproduction of hard polymer blends. In contrast, there is a growingdemand for a wide variety of articles that are soft and soothing to thetouch. It is also important for these articles to have strength,durability, nontacky and good balance of oil resistance and compressionset required by the applications. There is therefore significantinterest in producing heterogeneous polymer blends having a high contentof cross-linked elastomer.

SUMMARY

In one aspect, the present invention resides in a heterogeneous polymerblend comprising:

-   -   (a) a dispersed phase comprising a thermoplastic first polymer        having a crystallinity of at least 30%; and    -   (b) a continuous phase comprising a second polymer different        from the first polymer, the second polymer having a        crystallinity of less than 20% and being at least partially        cross-linked.

Preferably, said second polymer is at least partially cross-linked suchthat at least a fraction of said continuous phase is insoluble inxylene. Conveniently, said fraction insoluble in xylene comprises atleast 5%, such as at least 10%, such as at least 20%, such as at least30%, by weight of said continuous phase.

Preferably, said dispersed phase comprises particles of saidthermoplastic first polymer having an average particle size less than 10microns, preferably less than 5 microns, more preferably less than 3micron.

Conveniently, the polymer blend is substantially free of processing oiland curative.

In one embodiment, no more than about 70 wt %, preferably no more thanabout 50 wt %, and more preferably no more than 30 wt %, of the secondpolymer is extractable in cyclohexane at 23° C.

Conveniently, said dispersed phase comprises less than 50 wt %, such asless than 30 wt %, for example less than 20 wt % of the totalheterogeneous polymer blend.

Preferably, said thermoplastic first polymer is a homopolymer of a C₂ toC₂₀ olefin or a copolymer of a C₂ to C₂₀ olefin with less than 15 wt %of at least one comonomer.

Preferably, the second polymer is produced from a plurality ofcomonomers comprising at least one C₃ to C₂₀ olefin and at least onepolyene. Conveniently, the polyene has at least two polymerizableunsaturated groups and preferably is a diene.

In a further aspect, the invention resides in a process for producing aheterogeneous polymer blend comprising (a) a dispersed phase comprisinga thermoplastic first polymer having at least 30% crystallinity; and (b)a continuous phase comprising a second polymer different from the firstpolymer, the second polymer having a crystallinity less than that of thefirst polymer and being at least partially cross-linked, the processcomprising:

-   -   (i) polymerizing at least one first monomer to produce the        thermoplastic first polymer;    -   (ii) contacting at least part of said first polymer with at        least one second monomer and at least one polyene under        conditions sufficient to polymerize said second monomer to        produce, and simultaneously cross-link, said second polymer as        finely divided particles.

In one embodiment, the product of said contacting (ii) is subjected toan additional curing step to further cross-link said second polymer.

In yet a further aspect, the present invention resides in a process forproducing a heterogeneous polymer blend, the process comprising:

-   -   (a) selecting a catalyst capable of polymerizing a C₂ to C₂₀        olefin to produce a first polymer having at least 30%        crystallinity;    -   (b) contacting said catalyst with one or more C₂ to C₂₀ olefins        at a temperature of at least 50° C. to produce a first polymer        having at least 30% crystallinity;    -   (c) contacting said first polymer and said catalyst with at        least one C₃ to C₂₀ olefin and at least one polyene under        conditions sufficient to polymerize said at least one C₃ to C₂₀        olefin to produce, and simultaneously cross-link, a second        polymer, whereby the product of said contacting (c) is a        heterogeneous polymer blend comprising a dispersed phase of the        first polymer having at least 30% crystallinity and a continuous        phase of said second polymer, wherein said second polymer is at        least partially cross-linked and comprises at least 15 wt % of        said C₃ to C₂₀ olefin and at least 0.0001 wt % of said polyene.

Conveniently, said polyene has at least two polymerizable unsaturatedgroups.

Conveniently, said catalyst selected in (a) is a single site catalystcomprising at least one catalyst component, normally a metallocene, andat least one activator.

In still yet a further aspect, the present invention resides in aprocess for producing a heterogeneous polymer blend, the processcomprising:

-   -   (a) selecting a catalyst capable of polymerizing a C₂ to C₂₀        olefin to produce a first polymer having at least 30%        crystallinity;    -   (b) contacting said catalyst with one or more C₂ to C₂₀ olefins        at a temperature of at least 50° C. to produce a first polymer        having at least 30% crystallinity;    -   (c) contacting said first polymer together with at least one C₃        to C₂₀ olefin and at least one polyene with a catalyst capable        of polymerizing bulky monomers under conditions sufficient to        polymerize said at least one C₃ to C₂₀ olefin to produce, and        simultaneously cross-link, a second polymer, whereby the product        of said contacting (c) is a heterogeneous polymer blend        comprising a dispersed phase of the first polymer having at        least 30% crystallinity and a continuous phase of said second        polymer, wherein said second polymer is at least partially        cross-linked and comprises at least 15 wt % of said C₃ to C₂₀        olefin and at least 0.0001 wt % of said polyene.

In one embodiment, the catalyst employed in contacting (c) is the sameas the catalyst employed in contacting (b).

In another embodiment, the catalyst employed in contacting (c) is thedifferent from the catalyst employed in contacting (b) and catalystquenching is applied between the contacting (b) and the contacting (c).

In one embodiment, the product of said contacting (c) is subjected to anadditional curing step to further cross-link said second polymer.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an atomic force micrograph (AFM) of the polymer blend producedin Example 1.

FIG. 2 is an atomic force micrograph (AFM) of the polymer blend producedin Example 2.

DETAILED DESCRIPTION

For purposes of this invention and the claims thereto when a polymer oroligomer is referred to as comprising an olefin, the olefin present inthe polymer or oligomer is the polymerized or oligomerized form of theolefin, respectively. Likewise the use of the term polymer is meant toencompass homopolymers and copolymers. In addition the term copolymerincludes any polymer having 2 or more monomers. Thus, as used herein,the term “polypropylene” means a polymer made of at least 50% propyleneunits, preferably at least 70% propylene units, more preferably at least80% propylene units, even more preferably at least 90% propylene units,even more preferably at least 95% propylene units or 100% propyleneunits.

As used herein, the term “heterogeneous blend” means a compositionhaving two or more morphological phases in the same state. For example ablend of two polymers where one polymer forms discrete packets (orfinely divided phase domains) dispersed in a matrix of another polymeris said to be heterogeneous in the solid state. Also a heterogeneousblend is defined to include co-continuous blends where the blendcomponents are separately visible, but it is unclear which is thecontinuous phase and which is the discontinuous phase. Such morphologyis determined using scanning electron microscopy (SEM) or atomic forcemicroscopy (AFM). In the event the SEM and AFM provide different data,then the AFM data are used. By continuous phase is meant the matrixphase in a heterogeneous blend. By discontinuous phase is meant thedispersed phase in a heterogeneous blend. The finely divided phasedomains of the discontinuous phase are also referred as particles.

In contrast, a “homogeneous blend” is a composition having substantiallyone morphological phase in the same state. For example a blend of twopolymers where one polymer is miscible with another polymer is said tobe homogeneous in the solid state. Such morphology is determined usingscanning electron microscopy. By miscible is meant that that the blendof two or more polymers exhibits single-phase behavior for the glasstransition temperature, e.g. the Tg would exist as a single, sharptransition temperature on a dynamic mechanical thermal analyzer (DMTA)trace of tan δ (i.e., the ratio of the loss modulus to the storagemodulus) versus temperature. By contrast, two separate transitiontemperatures would be observed for an immiscible blend, typicallycorresponding to the temperatures for each of the individual componentsof the blend. Thus a polymer blend is miscible when there is one Tgindicated on the DMTA trace. A miscible blend is homogeneous, while animmiscible blend is heterogeneous.

As used herein the term “substantially free of processing oil” meansthat the relevant product contains little or no of the oil-basedprocessing aids, such as extender oils, synthetic processing oils,oligomeric extenders, or a combination thereof, that are added toconventional polymer blends to control the rheological characteristicsof the blends during dynamic vulcanization. Preferably the relevantproduct contains less than 1 weight % processing oil, more preferablyless than 0.5 weight %, most preferably less than 0.1 weight %,processing oil. The amount of oil in the polymer blend is determinedusing solvent extraction as described the example section.

By virtue of the fact that the second polymer of the polymer blend ofthe invention is formed as at least partially cross-linked particles inthe polymerization reactor, the need for a subsequent dynamicvulcanization step and hence the need for addition of processing oil canbe avoided. It is, however, to be appreciated that in some cases thepolymer blend of the invention may be subjected to post-polymerizationcuring and/or vulcanization to produce additional cross-linking of thesecond polymer.

As used herein the term “curative” means any of the additivesconventionally added to polymer blends to effect curing of one or morecomponents of the blend during a post-polymerization, dynamicvulcanization step. Examples of known curatives include sulfur, sulfurdonors, metal oxides, resin systems, such as phenolic resins,peroxide-based systems, hydrosilation with platinum or peroxide and thelike, both with and without accelerators and coagents.

The term dynamic vulcanization refers to a vulcanization or curingprocess for a rubber contained in a blend with a thermoplastic resin,wherein the rubber is crosslinked or vulcanized under conditions of highshear at a temperature above the melting point of the thermoplastic.Dynamic vulcanization can occur in the presence of a processing oil, orthe oil can be added after dynamic vulcanization (i.e., post added), orboth (i.e., some can be added prior to dynamic vulcanization and somecan be added after dynamic vulcanization).

As used herein the term “bulky monomer” means an olefin monomer that isnot a linear C₂ to C₂₀ alpha olefin. Bulky monomers include cyclicolefin monomers, such as 5-ethylidene-2-norbornadiene (ENB),5-vinyl-2-norbornene (VNB) and cyclopentadiene; branched olefinmonomers, such as 3,5,5 trimethyl hexene-1; and macromonomers, such asterminally unsaturated oligomers or terminally unsaturated polymers.

As used herein, the term “terminal unsaturation” is defined to meanvinyl unsaturation, vinylene unsaturation or vinylidene unsaturation ona polymer chain end, with vinyl unsaturation being preferred.

This invention relates to a heterogeneous polymer blend comprising asemi-crystalline (at least 30% crystalline) thermoplastic first polymerthat constitutes the dispersed phase and a continuous phase of a secondpolymer different from, and less crystalline than, the first polymer.The second polymer is at least partially cross-linked as a result of anin-situ reaction between a polyene and the second polymer that takesplace concurrently with the polymerization of the second polymer. Thepresence and amount of such partially cross-linked polymers in the blendcan be determined by a multi-step solvent extraction process. In thisprocess the direct product of the polymerization process, withoutundergoing any additional curing steps, is first contacted withcyclohexane at 25° C. for 48 hours to dissolve the uncross-linked andlightly branched elastomeric components of the blend and then theremaining solids are refluxed at the boiling temperature of xylene for24 hours with xylene to isolate the “at least partially cross-linkedpolymer”. The “at least partially cross-linked polymer” is also referredto herein as “xylene insolubles”. Details of the solvent extractionprocedure are given in the Examples.

The heterogeneous polymer blends of the present invention contain hybridpolymer. While not wishing to bound by theory, it is believed thatreactive intermediates generated in the polymerization of the firstpolymer engage in the polymerization processes taking place in theformation of the second polymer, producing hybrid polymers (also knownas branch-block copolymers) that combine the characteristics of thefirst and second polymers, such as the melting temperature of the firstpolymer and the lower glass transition temperatures of the secondpolymer.

This invention also relates to a process for making the above polymerblend. In a reactor, a semi-crystalline polymer is produced in a firstpolymerization step. In a second polymerization step, the elastomericpolymer is synthesized, in the presence of the semi-crystalline polymerphase. The elastomer is crosslinked through the use of multifunctionalmonomers, particularly a polyene having at least two polymerizableunsaturated groups, with the degree of crosslinking being controlled bythe reaction environment during the polymerization.

Following the two polymerization steps, the product composition can beoptionally subjected to a dynamic vulcanization step to enhance thedegree of cross-linking of the elastomeric phase.

The First Polymer

The dispersed phase of the present heterogeneous polymer blend may beany crystalline or semi-crystalline thermoplastic polymer or a mixturethereof. Useful thermoplastic polymers have a crystallinity of at least30%, more preferably at least 40% as determined by differential scanningcalorimetry (DSC). The first polymer provides the composition withrequired tensile strength and temperature resistance. Accordingly,semi-crystalline polymers with a melting temperature, as measured byDSC, above 100° C., preferably above 120° C., preferably above 140° C.are desired. Typically, the first polymer has a crystallizationtemperature (Tc) between about 20 and about 120° C., such as betweenabout 70 and about 110° C. Polymers with a high glass transitiontemperature to provide the elevated temperature resistance are alsoacceptable as the thermoplastic dispersed phase.

Exemplary thermoplastic polymers include the family of polyolefinresins, polyesters (such as polyethylene terephthalate, polybutyleneterephthalate), polyamides (such as nylons), polycarbonates,styrene-acrylonitrile copolymers, polystyrene, polystyrene derivatives,polyphenylene oxide, polyoxymethylene, and fluorine-containingthermoplastics. The preferred thermoplastic resins are crystallinepolyolefins that are formed by polymerizing C₂ to C₂₀ olefins such as,but not limited to, ethylene, propylene and C₄ to C₁₂ α-olefins, such as1-butene, 1-hexene, 1-octene, 2-methyl-1-propene, 3-methyl-1-pentene,4-methyl-1-pentene, 5-methyl-1-hexene, and mixtures thereof. Copolymersof ethylene and propylene or ethylene or propylene with anotherα-olefin, such as butene-1;pentene-1,2-methylpentene-1,3-methylbutene-1;hexene-1,3-methylpentene-1,4-methylpentene-1,3,3-dimethylbutene-1;heptene-1; hexene-1; methylhexene-1; dimethylpentene-1trimethylbutene-1; ethylpentene-1; octene-1; methylpentene-1;dimethylhexene-1; trimethylpentene-1; ethylhexene-1;methylethylpentene-1; diethylbutene-1; propylpentane-1; decene-1;methylnonene-1; nonene-1; dimethyloctene-1; trimethylheptene-1;ethyloctene-1; methylethylbutene-1; diethylhexene-1 and dodecene-1, mayalso be used.

In one embodiment, the thermoplastic polymer comprises a propylenehomopolymer, or a mixture of propylene homopolymers and copolymers.Typically, the propylene polymer is predominately crystalline, i.e., ithas a melting point generally greater than 110° C., alternativelygreater than 115° C., and preferably greater than 130° C. The term“crystalline,” as used herein, characterizes those polymers that possesshigh degrees of inter- and intra-molecular order in the solid state.Heat of fusion, a measure of crystallinity, greater than 60 J/g,alternatively at least 70 J/g, alternatively at least 80 J/g, asdetermined by DSC analysis, is preferred. The heat of fusion isdependent on the composition of the polypropylene. A propylenehomopolymer will have a higher heat of fusion than a copolymer or blendof a homopolymer and copolymer.

Where the thermoplastic polymer is a copolymer of propylene, thedispersed phase can vary widely in composition. For example, propylenecopolymer containing 10 weight percent or less of a comonomer withpredominant isotactic propylene crystalline sequence can be used (i.e.,at least 90% by weight propylene). Further, polypropylene segments maybe part of graft or block copolymers having a sharp melting point above110° C. and alternatively above 115° C. and alternatively above 130° C.,characteristic of the stereoregular propylene sequences. The dispersedphase may be a combination of homopolypropylene, and/or random, and/orblock copolymers as described herein. When the dispersed phase is arandom copolymer, the percentage of the copolymerized alpha-olefin inthe copolymer is, in general, up to 9% by weight, alternatively 0.5% to8% by weight, alternatively 2% to 6% by weight. The preferredalpha-olefins contain 2 or from 4 to 12 carbon atoms. One, two or morealpha-olefins can be copolymerized with propylene.

The dispersed particles of the first polymer typically have an averagesize of less than 10 microns, preferably less than 5 microns, morepreferably less than 3 microns.

The Second Polymer

The continuous second polymer phase of the heterogeneous polymer blendof the invention comprises an amorphous or low crystallinity (having acrystallinity of less than 20%) polymer. The second polymer phase isgenerally an elastomeric copolymer that is polymerized and at the sametime cross-linked in the presence of the first polymer. Somenon-limiting examples of suitable elastomers for use as the secondpolymer phase include olefin copolymers, butyl rubber, styrene-butadienecopolymer rubber, butadiene rubber, acrylonitrile rubber, halogenatedrubber such as brominated and chlorinated isobutylene-isoprene copolymerrubber, butadiene-styrene-vinyl pyridine rubber, urethane rubber,polyisoprene rubber, epichlolorohydrin terpolymer rubber, andpolychloroprene. The second polymer of the heterogeneous polymer blendof the invention can also comprise atactic polymers such as atacticpolypropylene. The preferred second polymers are elastomeric olefincopolymers.

Suitable elastomeric copolymers for use in the present invention arecopolymers produced by copolymerizing two or more alpha olefins with atleast one polyene, normally a diene. More typically, the elastomericcomponent is a copolymer of ethylene with at least one alpha-olefinmonomer, and at least one diene monomer. The alpha-olefins may include,but are not limited to, C₃ to C₂₀ alpha-olefins, such as propylene,butene-1, hexene-1, 4-methyl-1 pentene, octene-1, decene-1, orcombinations thereof. The preferred alpha-olefins are propylene,hexene-1, octene-1 or combinations thereof. Thus, for example, thesecond polymer can be an ethylene-propylene-diene (commonly called“EPDM”). Typically, the second polymer contains at least 15 wt % of theC₃ to C₂₀ olefin and at least 0.0001 wt % of the diene.

Cross-linking of the second polymer phase is facilitated by the presenceof a polyene that in one embodiment has at least two unsaturated bondsthat can readily be incorporated into the polymer to form the desiredcross-linked system. Examples of such polyenes include α,ω-dienes (suchas butadiene, 1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene,1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1.10-undecadiene,1,11-dodecadiene, 1,12-tridecadiene, and 1,13-tetradecadiene) andcertain multi-ring alicyclic fused and bridged ring dienes (such astetrahydroindene; norbomdiene; methyl-tetrahydroindene;dicyclopentadiene; bicyclo-(2.2.1)-hepta-2,5-diene; and alkenyl-,alkylidene-, cycloalkenyl-, and cylcoalkyliene norbornenes [including,e.g., 5-methylene-2-norbornene, 5-ethylidene-2-norbornene,5-propenyl-2-norbornene, 5-isopropylidene-2-norbornene,5-(4-cyclopentenyl)-2-norbornene, 5-cyclohexylidene-2-norbornene, and5-vinyl-2-norbornene]).

In further embodiment, the polyene has at least two unsaturated bondswherein one of the unsaturated bonds is readily incorporated into apolymer. The second bond may partially take part in polymerization toform cross-linked polymers but normally provides at least someunsaturated bonds in the polymer product suitable for subsequentfunctionalization (such as with maleic acid or maleic anhydride), curingor vulcanization in post polymerization processes. Examples of polyenesaccording to said further embodiment include, but are not limited tobutadiene, pentadiene, hexadiene, heptadiene, octadiene, nonadiene,decadiene, undecadiene, dodecadiene, tridecadiene, tetradecadiene,pentadecadiene, hexadecadiene, heptadecadiene, octadecadiene,nonadecadiene, icosadiene, heneicosadiene, docosadiene, tricosadiene,tetracosadiene, pentacosadiene, hexacosadiene, heptacosadiene,octacosadiene, nonacosadiene, triacontadiene, and polybutadienes havinga molecular weight (M_(w)) of less than 1000 g/mol. Examples of straightchain acyclic dienes include, but are not limited to 1,4-hexadiene and1,6-octadiene. Examples of branched chain acyclic dienes include, butare not limited to 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene,and 3,7-dimethyl-1,7-octadiene. Examples of single ring alicyclic dienesinclude, but are not limited to 1,4-cyclohexadiene, 1,5-cyclooctadiene,and 1,7-cyclododecadiene. Examples of multi-ring alicyclic fused andbridged ring dienes include, but are not limited to tetrahydroindene;norbomadiene; methyl-tetrahydroindene; dicyclopentadiene; bicyclo-(2.2.1)-hepta-2,5-diene; and alkenyl-, alkylidene-, cycloalkenyl-, andcylcoalkyliene norbornenes [including, e.g., 5-methylene-2-norbornene,5-ethylidene-2-norbornene, 5-propenyl-2-norbornene,5-isopropylidene-2-norbornene, 5-(4-cyclopentenyl)-2-norbornene,5-cyclohexylidene-2-norbornene, and 5-vinyl-2-norbornene]. Examples ofcycloalkenyl-substituted alkenes include, but are not limited to vinylcyclohexene, allyl cyclohexene, vinyl cyclooctene, 4-vinyl cyclohexene,allyl cyclodecene, vinyl cyclododecene, and tetracyclo(A-11,12)-5,8-dodecene.

Generally, olefins are present in the elastomeric phase of theheterogeneous polymer blend of the invention at levels from about 95 toabout 99.99 wt %, whereas the diene content of the elastomeric copolymeris from about 0.01 wt % to about 5 wt %. But specific embodiments canhave a variety of diene contents. Some embodiments have two or moredifferent olefin units in the elastomeric component, with at least onemonomer being selected from ethylene, propylene and C₄ to C₂₀alpha-olefins. Typically, said at least one monomer unit comprisesethylene and a further monomer is selected from propylene and C₄ to C₁₂alpha-olefins, especially propylene. These embodiments typically haveone olefin present in amounts of from 12 to 98 wt %, for example from 30to 95 wt %, of the copolymer whereas the other olefin is present inamounts of from 2 to 88 wt %, for example from 2 to 30 wt %, of thecopolymer.

Still more desirably, the copolymer includes: ethylene units in therange from 2 wt % to 88 wt % of the copolymer; propylene or otherα-olefin(s) units in the range from 98 wt % to 12 wt %, desirablyethylene units in the range from 5 to 20 wt % and propylene or otherα-olefin(s) units in the range from 95 to 80 wt %; more desirablyethylene units in the range from 5 wt % to 15 wt % and propylene orother α-olefin(s) units in the range from 95 to 85 wt % of thecopolymer.

During the second polymerization step to produce the elastomeric phase,it is believed that a distribution of cross-products are formedemanating principally from the grafting of the first thermoplasticpolymer to the second elastomeric polymer. These hybrid cross-products,also known as branch-block copolymers, form when reactive intermediates(macromonomers) from the first polymerization step cross-over into thesecond polymerization step and participate in the polymerization of thesecond polymer. The presence of branch-block copolymers is believed toinfluence the events occurring during the polymerization as well asproduct properties. The extent of influence depends on the populationdistribution of the branch-block copolymer fraction.

The elastomeric second polymer is the continuous phase in the presentheterogeneous polymer blend. In some cases, the elastomeric secondpolymer may be formed as finely divided particles and coated with thefirst polymer though the second polymer is visually the continuous phasein AFM images.

The amount of second polymer relative to the first polymer may varywidely depending on the nature of the polymers and the intended use ofthe final polymer blend. In particular, however, one advantage of theprocess of the invention is the ability to be able to produce aheterogeneous polymer blend in which the elastomeric second polymercomprise more than 50 wt %, such as more than 60 wt %, for example morethan 70 wt % of the total heterogeneous polymer blend and thecrystalline first polymer comprises less than 50 wt %, such as less than30 wt %, for example less than 20 wt % of the total heterogeneouspolymer blend.. For TPV applications, the weight ratio of the secondpolymer to the first polymer is generally from about 90:10 to about50:50, more preferably from about 80:20 to about 60:40.

Production of the Polymer Blend

The polymer blend is produced by a two-step polymerization process. Inthe first step, a crystalline thermoplastic polymer is produced bypolymerizing at least one first monomer in one or more polymerizationzones. The effluent from the first step is then fed into a secondpolymerization step where an elastomer is produced in the presence ofthe polymer produced in the first step. The elastomer is in-situcross-linked, at least partially, in the second polymerization zone. Itis believed that the cross-linked elastomer forms finely dividedmicrogel particles that ensure that the polymer blend isthermo-processable.

In an alternative embodiment, the first step of polymerization isreplaced with addition of pre-made crystalline thermoplastic polymer.The pre-made polymer can be produced in a separate system or can be acommercially available product. The crystalline thermoplastic polymercan be dissolved in a solvent and then added into a reaction medium forthe second polymerization step. The crystalline thermoplastic polymercan be also ground into fine powder and then added into the reactionmedium for the second polymerization step.

Any known polymerization process may be used to produce thethermoplastic polymer. For example, the polymer may be a propylenehomopolymer obtained by homopolymerization of propylene in a singlestage or multiple stage reactor. Copolymers may be obtained bycopolymerizing propylene and an alpha-olefin having 2 or from 4 to 20carbon atoms in a single stage or multiple stage reactor. Polymerizationmethods include high pressure, slurry, gas, bulk, suspension,supercritical, or solution phase, or a combination thereof, using atraditional Ziegler-Natta catalyst or a single-site metallocene catalystsystem, or combinations thereof including bimetallic (i.e, Z/N and/ormetallocene) catalysts. Preferred catalysts are those capable ofpolymerizing a C₂ to C₂₀ olefin to produce a first polymer having atleast 30% crystallinity and at least 0.01% terminal unsaturation. Thecatalysts can be in the form of a homogeneous solution, supported, or acombination thereof. Polymerization may be carried out by a continuous,a semi-continuous or batch process and may include use of chain transferagents, scavengers, or other such additives as deemed applicable. By“continuous” is meant a system that operates (or is intended to operate)without interruption or cessation. For example a continuous process toproduce a polymer would be one where the reactants are continuallyintroduced into one or more reactors and polymer product is continuallywithdrawn.

Where the thermoplastic dispersed phase comprises a polyolefin, such asa propylene polymer or copolymer, the polyolefin will generally beproduced in the presence of a single site catalyst, preferably ametallocene catalyst, with an activator and optional scavenger.Preferred metallocene catalysts are those capable of polymerizing a C₂to C₂₀ olefin to produce a first polymer having at least 30%crystallinity.

Preferred metallocene catalysts useful for producing the thermoplasticfirst polymer in the process of the invention are not narrowly definedbut generally it is found that the most suitable are those in thegeneric class of bridged, substituted bis(cyclopentadienyl)metallocenes, specifically bridged, substituted bis(indenyl)metallocenes known to produce high molecular weight, high melting,highly isotactic propylene polymers. Particularly suitable catalysts arebridged bis-indenyl metallocene catalysts having a substituent on one orboth of the 2- and 4- positions on each indenyl ring or those having asubstituent on the 2-, 4-, and 7- positions on each indenyl ring.Generally speaking, those of the generic class disclosed in U.S. Pat.No. 5,770,753 (fully incorporated herein by reference) should besuitable, however, it has been found that the exact polymer obtained isdependent on the metallocene's specific substitution pattern, amongother things. A specific list of useful catalyst compounds is found inInternational Patent Publication No. WO 2004/026921 at page 29 paragraph[00100] to page 66, line 4. In another embodiment, the catalystcompounds described in International Patent Publication No. WO2004/026921 at page 66, paragraph [00103] to page 70, line 3 may also beused in the practice of this invention.

Particularly preferred are racemic metallocenes, such asrac-dimethylsiladiyl(2-isopropyl,4-phenylindenyl)₂ zirconium dichloride;rac-dimethylsiladiyl(2-isopropyl,4-[1-naphthyl]indenyl)₂ zirconiumdichloride;rac-dimethylsiladiyl(2-isopropyl,4-[3,5-dimethylphenyl]indenyl)₂zirconium dichloride;rac-dimethylsiladiyl(2-isopropyl,4-[ortho-methyl-phenyl]indenyl)₂zirconium dichloride; rac-dimethylsilyl bis-(2-methyl,4-phenylindenyl)zirconium dichoride, rac dimethylsiladlyl bis-(2-methyl,4-napthylindenyl) zirconium dichloride, rac-dimethylsiladiyl(2-isopropyl, 4-[3,5 di-t-butyl-phenyl]indenyl)₂ zirconiumdichloride; rac-dimethyl siladiyl(2-isopropyl,4-[orthophenyl-phenyl]indenyl)₂ zirconium dichloride,rac-diphenylsiladiyl(2-methyl-4-[1-naphthyl]indenyl)₂ zirconiumdichloride and rac-biphenyl siladiyl(2-isopropyl, 4-[3,5di-t-butyl-phenyl]indenyl)₂ zirconium dichloride. Alkylated variants ofthese metallocenes (e.g. dimethyl instead of dichloride) are alsouseful, particularly when combined with a non-coordinating anion typeactivator. These and other metallocene compositions are described indetail in U.S. Pat. Nos. 6,376,407, 6,376,408, 6,376,409, 6,376,410,6,376,411, 6,376,412, 6,376,413, 6,376,627, 6,380,120, 6,380,121,6,380,122, 6,380,123, 6,380,124, 6,380,330, 6,380,331, 6,380,334,6,399,723 and 6,825,372.

The manner of activation of the catalyst used in the firstpolymerization step can vary. Alumoxane and preferably methyl alumoxane(MAO) can be used. Non-or weakly coordinating anion activators (NCA) maybe obtained in any of the ways described in EP277004, EP426637.Activation generally is believed to involve abstraction of an anionicgroup such as the methyl group to form a metallocene cation, althoughaccording to some literature zwitterions may be produced. The NCAprecursor can be an ion pair of a borate or aluminate in which theprecursor cation is eliminated upon activation in some manner, e.g.trityl or ammonium derivatives of tetrakis pentafluorophenyl boron (SeeEP277004). The NCA precursor can be a neutral compound such as a borane,which is formed into a cation by the abstraction of and incorporation ofthe anionic group abstracted from the metallocene (See EP426638).

The alumoxane activator may be utilized in an amount to provide a molaraluminum to metallocene ratio of from 1:1 to 20,000:1 or more. Thenon-coordinating compatible anion activator may be utilized in an amountto provide a molar ratio of metallocene compound to non-coordinatinganion of 10:1 to 1:1.

Particularly useful activators include dimethylaniliniumtetrakis(pentafluorophenyl) borate and dimethyl aniliniumtetrakis(heptafluoro-2-naphthyl) borate. For a more detailed descriptionof useful activators, see International Patent Publication No. WO2004/026921 at page 72, paragraph [00119] to page 81 paragraph [00151].A list of particularly useful activators that can be used in thepractice of this invention may be found at page 72, paragraph [00177] topage 74, paragraph [00178] of International Patent Publication No. WO2004/046214.

Preferably, the first polymerization step is conducted in a continuous,stirred tank reactor. Tubular reactors equipped with the hardware tointroduce feeds, catalysts and cross-linking agents in staged manner canalso be used. Generally, polymerization reactors are agitated (stirred)to reduce or avoid concentration gradients. Reaction environmentsinclude the case where the monomer(s) acts as diluent or solvent as wellas the case where a liquid hydrocarbon is used as diluent or solvent.Preferred hydrocarbon liquids include both aliphatic and aromatic fluidssuch as desulphurized light virgin naphtha and alkanes, such as propane,isobutane, mixed butanes, hexane, pentane, isopentane, cyclohexane,isooctane, and octane. In an alternate embodiment a perfluorocarbon orhydrofluorocarbon is used as the solvent or diluent.

Suitable conditions for the first polymerization step include atemperature from about 50 to about 250° C., preferably from about 50 toabout 150° C., more preferably from about 70 to about 150° C. and apressure of 0.1 MPa or more, preferably 2 MPa or more. The upperpressure limit is not critically constrained but is typically 200 MPa orless, preferably, 120 MPa or less, except when operating insupercritical phase then the pressure and temperature are above thecritical point of the reaction media in question (typically over 95° C.and 4.6 MPa for propylene polymerizations). For more information onrunning supercritical polymerizations, see International PatentPublication No. WO 2004/026921. Temperature control in the reactor isgenerally obtained by balancing the heat of polymerization with reactorcooling via reactor jackets or cooling coils, auto refrigeration,pre-chilled feeds, vaporization of liquid medium (diluent, monomers orsolvent) or combinations of all three. Adiabatic reactors withpre-chilled feeds may also be used.

In the second polymerization step, some or all of the first polymerformed in the first polymerization step is contacted with at least onesecond monomer, typically ethylene and a C₃ to C₂₀ olefin, and at leastone cross-linking agent, typically a diene, under conditions sufficientto polymerize the second monomer(s) to produce the second polymer andalso cross-link said second polymer. As a result of the cross-linkingthat occurs with the second polymerization step, the product of thesecond polymerization step contains at least a fraction which isinsoluble in xylene. Preferably, the amount of said xylene insolublefraction by weight of the second polymer, also referred to herein as thedegree of cross-link of the second polymer, is at least 4%, such as atleast 10%, such as at least 20%, such as at least 40%, such as at least50%.

Any known polymerization process, including solution, suspension,slurry, supercritical and gas phase polymerization processes, and anyknown polymerization catalyst can be used to produce the second polymercomponent. Generally, the catalyst used to produce the second polymercomponent should be capable of polymerizing bulky monomers and also becapable of producing a polymer having an Mw of 20,000 or more and acrystallinity of less than 20%.

In one embodiment, the catalyst employed to produce the second polymercomponent is the same as, or is compatible with, the catalyst used toproduce the thermoplastic first polymer. In such a case, the first andsecond polymerization zones can be in a multiple-zone reactor, orseparate, series-connected reactors, with the entire effluent from thefirst polymerization zone, including any active catalyst, beingtransferred to the second polymerization zone. Additional catalyst canthen be added, as necessary, to the second polymerization zone, in whichcase the elastomeric second polymer is derived from both the catalystsintroduced into the first and the second polymerization zones. In aparticularly preferred embodiment, the process of the invention isconducted in two or more series-connected, continuous flow, stirred tankor tubular reactors using metallocene catalysts.

In another embodiment, catalyst quenching is applied between the twopolymerization zones and a separate catalyst is introduced in the secondreaction zone to produce the elastomer component. Catalyst quenchingagents (such as air or an alcohol) may be introduced into the effluentfrom the first polymerization zone right after the reactor exit todeactivate the catalyst used for the first polymerization. Scavengersmay be useful and can be fed into the effluent downstream of thecatalyst quenching agent injection point or the second polymerizationzone.

Where a separate catalyst is used to produce the elastomeric secondpolymer, this is conveniently one of, or a mixture of, metallocenecompounds of either or both of the following types:

-   -   1) Cyclopentadienyl (Cp) complexes which have two Cp ring        systems for ligands. The Cp ligands form a sandwich complex with        the metal and can be free to rotate (unbridged) or locked into a        rigid configuration through a bridging group. The Cp ring        ligands can be like or unlike, unsubstituted, substituted, or a        derivative thereof such as a heterocyclic ring system which may        be substituted, and the substitutions can be fused to form other        saturated or unsaturated rings systems such as        tetrahydroindenyl, indenyl, or fluorenyl ring systems. These        cyclopentadienyl complexes are represented by the formula        (Cp¹R¹ _(m))R³ _(n)(C_(p) ²R² _(p))MX_(q)        wherein Cp¹ of ligand (Cp¹R¹ _(m))and Cp² of ligand (Cp²R² _(p))        are the same or different cyclopentadienyl rings, R¹ and R² each        is, independently, a halogen or a hydrocarbyl, halocarbyl,        hydrocarbyl-substituted organometalloid or        halocarbyl-substituted organometalloid group containing up to        about 20 carbon atoms, m is 0, 1, 2, 3, 4, or 5, p is 0, 1, 2,        3, 4 or 5, and two R¹ and/or R² substituents on adjacent carbon        atoms of the cyclopentadienyl ring associated there with can be        joined together to form a ring containing from 4 to about 20        carbon atoms, R³ is a bridging group, n is the number of atoms        in the direct chain between the two ligands and is 0, 1, 2, 3,        4, 5, 6, 7, or 8, preferably 0, 1, 2, or 3, M is a transition        metal having a valence of 3, 4, 5 or 6, preferably from Group 4,        5, or 6 of the Periodic Table of the Elements and is preferably        in its highest oxidation state, each X is a non-cyclopentadienyl        ligand and is, independently, a halogen or a hydrocarbyl,        oxyhydrocarbyl, halocarbyl, hydrocarbyl-substituted        organometalloid, oxyhydrocarbyl-substituted organometalloid or        halocarbyl-substituted organometalloid group containing up to        about 20 carbon atoms, q is equal to the valence of M minus 2.    -   2) Monocyclopentadienyl complexes which have only one Cp ring        system as a ligand. The Cp ligand forms a half-sandwich complex        with the metal and can be free to rotate (unbridged) or locked        into a rigid configuration through a bridging group to a        heteroatom-containing ligand. The Cp ring ligand can be        unsubstituted, substituted, or a derivative thereof such as a        heterocyclic ring system which may be substituted, and the        substitutions can be fused to form other saturated or        unsaturated rings systems such as tetrahydroindenyl, indenyl, or        fluorenyl ring systems. The heteroatom containing ligand is        bound to both the metal and optionally to the Cp ligand through        the bridging group. The heteroatom itself is an atom with a        coordination number of three from Group 15 or 16 of the periodic        table of the elements. These mono-cyclopentadienyl complexes are        represented by the formula        (Cp¹R¹ _(m))R³ _(n)(YR²)MX_(s)        wherein R¹ is, each independently, a halogen or a hydrocarbyl,        halocarbyl, hydrocarbyl-substituted organometalloid or        halocarbyl-substituted organometalloid group containing up to        about 20 carbon atoms, m is 0, 1, 2, 3, 4 or 5, and two R¹        substituents on adjacent carbon atoms of the cyclopentadienyl        ring associated therewith can be joined together to form a ring        containing from 4 to about 20 carbon atoms, R³ is a bridging        group, n is 0, or 1, M is a transition metal having a valence of        from 3, 4, 5, or 6, preferably from Group 4, 5, or 6 of the        Periodic Table of the Elements and is preferably in its highest        oxidation state, Y is a heteroatom containing group in which the        heteroatom is an element with a coordination number of three        from Group 15 or a coordination number of two from Group 16        preferably nitrogen, phosphorous, oxygen, or sulfur, R² is a        radical independently selected from a group consisting of C₁ to        C₂₀ hydrocarbon radicals, substituted C₁ to C₂₀ hydrocarbon        radicals, wherein one or more hydrogen atoms is replaced with a        halogen atom, and when Y is three coordinate and unbridged there        may be two R₂ groups on Y each independently a radical selected        from a group consisting of C₁ to C₂₀ hydrocarbon radicals,        substituted C₁ to C₂₀ hydrocarbon radicals, wherein one or more        hydrogen atoms is replaced with a halogen atom, and each X is a        non-cyclopentadienyl ligand and is, independently, a halogen or        a hydrocarbyl, oxyhydrocarbyl, halocarbyl,        hydrocarbyl-substituted organometalloid,        oxyhydrocarbyl-substituted organometalloid or        halocarbyl-substituted organometalloid group containing up to        about 20 carbon atoms, s is equal to the valence of M minus 2;        Cp¹ is a Cp ring.

Examples of suitable biscyclopentadienyl metallocenes of the typedescribed in Group 1 above for the invention are disclosed in U.S. Pat.Nos. 5,324,800; 5,198,401; 5,278,119; 5,387,568; 5,120,867; 5,017,714;4,871,705; 4,542,199; 4,752,597; 5,132,262; 5,391,629; 5,243,001;5,278,264; 5,296,434; and 5,304,614, all of which are incorporated byreference herein.

Illustrative, but not limiting examples of preferred biscyclopentadienylmetallocenes of the type described in Group 1 above for the inventionare the racemic isomers of:

-   -   μ-(CH₃)₂Si(indenyl)₂M(Cl)₂    -   μ-(CH₃)₂Si(indenyl)₂M(CH₃)₂    -   μ-(CH₃)₂Si(tetrahydroindenyl)₂M(Cl)₂    -   μ-(CH₃)₂Si(tetrahydroindenyl)₂M(CH₃)₂    -   μ-(CH₃)₂Si(indenyl)₂M(CH₂CH₃)₂    -   μ-(C₆H₅)₂C(indenyl)₂M(CH₃)₂        wherein M is chosen from a group consisting of Zr and Hf.

Examples of suitable unsymmetrical cyclopentadienyl metallocenes of thetype described in Group 1 above for the invention are disclosed in U.S.Pat. Nos. 4,892,851; 5,334,677; 5,416,228; and 5,449,651; and aredescribed in publication J Am. Chem. Soc. 1988, 110, 6255, all of whichare incorporated by reference herein.

Illustrative, but not limiting examples of preferred unsymmetricalcyclopentadienyl metallocenes of the type described in Group 1 above forthe invention are:

-   -   μ-(C₆H₅)₂C(cyclopentadienyl)(fluorenyl)M(R)₂    -   μ-(C₆H₅)₂C(3-methylcyclopentadienyl)(fluorenyl)M(R)₂    -   μ-(CH₃)₂C(cyclopentadienyl)(fluorenyl)M(R)₂    -   μ-(C₆H₅)₂C(cyclopentadienyl)(2-methylindenyl)M(R)₂    -   μ-(C₆H₅)₂C(3-methylcyclopentadienyl)(2-methylindenyl)M(R)₂    -   μ-(p-triethylsilylphenyl)₂C(cyclopentadienyl)(3,8-di-t-butylfluorenyl)        M(R)₂    -   μ-(C₆H₅)₂C(cyclopentadienyl)(2,7-dimethylindenyl)M(R)₂    -   μ-(CH₃)₂C(cyclopentadienyl)(2,7-dimethylindenyl)M(R)₂.        wherein M is chosen from the group consisting of Zr and Hf and R        is chosen from the group consisting of Cl and CH₃.

Examples of suitable monocyclopentadienyl metallocenes of the typedescribed in group 2 above for the invention are disclosed in U.S. Pat.Nos. 5,026,798; 5,057,475; 5,350,723; 5,264,405; 5,055,438 and aredescribed in International Patent Publication No. WO 96/002244, all ofwhich are incorporated by reference herein.

Illustrative, but not limiting examples of preferredmonocyclopentadienyl metallocenes of the type described in group 2 abovefor the invention are:

-   -   μ-(CH₃)₂Si(cyclopentadienyl)(1-adamantylamido)M(R)₂    -   μ-(CH₃)₂Si(3-tertbutylcyclopentadienyl)(1-adamantylamido)M(R)₂    -   μ-(CH₃)₂Si(tetramethylcyclopentadienyl)(1-adamantylamido)M(R)₂    -   μ-(CH₃)₂C(tetramethylcyclopentadienyl)(1-adamantylamido)M(R)₂    -   μ-(CH₃)₂Si(tetramethylcyclopentadienyl)(1-tertbutylamido)M(R)₂    -   μ-(CH₃)₂Si(fluorenyl)(1-tertbutylamido)M(R)₂    -   μ-(CH₃)₂Si(tetramethylcyclopentadienyl)(1-cyclododecylamido)M(R)₂    -   μ-(CH₃)₂C(tetramethylcyclopentadienyl)(1-cyclododecylamido)M(R)₂        wherein M is selected from a group consisting of Ti, Zr, and Hf        and wherein R is selected from Cl and CH₃.

Another class of organometallic complexes that are useful catalysts forproducing the second polymer component are those with diimido ligandsystems such as those described in International Patent Publication No.WO 96/23010, the entire contents of which are incorporated herein byreference.

The conditions in the second polymerization zone are arranged not onlyto copolymerize the elastomer monomers with the bifunctional monomer,such as a diene, but also to cause at least partial cross-linking ofresultant elastomer. Typical conditions in the second polymerizationzone include a temperature of about 10° C. to about 250° C. and apressure of about 0.1 MPa to about 200 MPa.

The second polymer, which is at least partially cross-linked in thecopolymerization reaction of olefins and dienes, may be prepared bysolution, suspension or slurry polymerization of the olefins and dieneunder conditions in which the catalyst site remains relatively insolubleand/or immobile so that the polymer chains are rapidly immobilizedfollowing their formation. Such immobilization is affected, for example,by (1) using a solid, insoluble catalyst, (2) maintaining thepolymerization below the crystalline melting point of thermoplasticpolymers made in the first step and (3) using low solvency solvent suchas a fluorinated hydrocarbon.

In a solution/suspension process, the uncrosslinked second polymers aredissolved (or are soluble) in the polymerization media. The secondpolymers are then phase separated from the reaction media to formmicro-particles when the polymers are cross-linked. This in-situcross-link and phase separation facilitates the process to producepolymers of high molecular weight.

By selecting the catalyst systems (i.e., catalyst and activator), thepolymerization reaction conditions, and/or by introducing a dienemodifier, some molecules of the first polymer(s) and the secondpolymer(s) can be linked together to produce branch-block structures.While not wishing to be bound by theory, the branch-block copolymer isbelieved to comprise an amorphous backbone having crystalline sidechains originating from the first polymer.

To effectively incorporate the polymer chains of the first polymer intothe growing chains of the second polymer, it is preferable that thefirst polymerization step produces macromonomers having reactivetermini, such as vinyl end groups. By macromonomers having reactivetermini is meant a polymer having twelve or more carbon atoms(preferably 20 or more, more preferably 30 or more, more preferablybetween 12 and 8000 carbon atoms) and having a vinyl, vinylidene,vinylene or other terminal group that can be polymerized into a growingpolymer chain. By capable of polymerizing macromonomer having reactivetermini is meant a catalyst component that can incorporate amacromonomer having reactive termini into a growing polymer chain. Vinylterminated chains are generally more reactive than vinylene orvinylidene terminated chains. Generally, it is desirable that the firstpolymerization step produces a first polymer having at least 0.01%terminal unsaturation.

Optionally the thermoplastic first polymers are copolymers of one ormore alpha olefins and one or more of monomers having at least twoolefinically unsaturated bonds. Both of these unsaturated bonds aresuitable for and readily incorporated into a growing polymer chain bycoordination polymerization using either the first or second catalystsystems independently such that one double bond is incorporated into thefirst polymer segments while another double bond is incorporated intothe second elastomeric polymer segments to form a branched blockcopolymer. In a preferred embodiment these monomers having at least twoolefinically unsaturated bonds are di-olefins, preferably di-vinylmonomers.

Polymers with bimodal distributions of molecular weight and compositioncan be produced by the polymerization process of the invention, by, forexample, controlling the polymerization conditions in the first and thesecond polymerization zones and selecting the catalysts for the firstand the second polymerizations, such as by using multiple catalysts ineach polymerization zone.

A polymer can be recovered from the effluent of either the firstpolymerization step or the second polymerization step by separating thepolymer from other constituents of the effluent using conventionalseparation means. For example, polymer can be recovered from eithereffluent by coagulation with a non-solvent such as isopropyl alcohol,acetone, or n-butyl alcohol, or the polymer can be recovered bystripping the solvent or other media with heat or steam. One or moreconventional additives such as antioxidants can be incorporated in thepolymer during the recovery procedure. Possible antioxidants includephenyl-beta-naphthylamine; di-tert-butylhydroquinone, triphenylphosphate, heptylated diphenylamine, 2,2′-methylene-bis(4-methyl-6-tert-butyl)phenol, and2,2,4-trimethyl-6-phenyl-1,2-dihydroquinoline. Other methods of recoverysuch as by the use of lower critical solution temperature (LCST)followed by devolatilization are also envisioned. The catalyst may bedeactivated as part of the separation procedure to reduce or eliminatefurther uncontrolled polymerization downstream the polymer recoveryprocesses. Deactivation may be effected by the mixing with suitablepolar substances such as water, whose residual effect following recyclecan be counteracted by suitable sieves or scavenging systems.

Properties of the Polymer Blend

By virtue of the novel polymerization process used in its production,the heterogeneous polymer blend of the invention not only comprisesparticles of the first polymer dispersed within a matrix of the secondpolymer but also at least a portion the continuous phase is cross-linkedand preferably comprises a hybrid species of said first and secondpolymers having characteristics of the first and second polymers such asa melting temperature, preferably of at least 100° C., in the xyleneinsoluble fraction.

The heterogeneous polymer blends are thermo-processable by conventionalplastic processing techniques such as injection molding, extrusion andcompression molding despite the factor that the elastomer is at leastpartially cross-linked. The continuous phase of the heterogeneouspolymer blend of the invention comprises at least a fraction which isinsoluble in xylene and which is substantially free of the curativesnormally added to polymers blends to effect cross-linking duringpost-polymerization, dynamic extrusion. By substantially free is meantthat the continuous phase contains less than 1,000 ppm, such as lessthan 100 ppm, such as less than 10 ppm, of a curative.

Since the present heterogeneous polymer blends are composedpredominantly of the elastomeric second polymer, articles producedtherefrom are soft and smooth in touch even without oil addition.

The individual components of the heterogeneous polymer blend of theinvention can readily be separated by solvent extraction. In a suitablesolvent extraction regime, the blend, without undergoing any additionalprocessing steps, is contacted with cyclohexane at 25° C. for 48 hoursto dissolve the uncross-linked and branched elastomeric components ofthe blend and then the remaining solids are refluxed at the boilingtemperature of xylene for 24 hours with xylene to dissolve thethermoplastic phase material. The remaining xylene insolubles comprisethe cross-linked second polymer and hybrid copolymers of the first andsecond polymers. These hybrid copolymers typically exhibit a meltingtemperature in excess of 100° C.

In one embodiment, the polymer blend described herein has a tensilestrength at break (as measured by ISO 37 at 23° C.) of 0.5 MPa or more,alternatively 0.75 MPa or more, alternatively 1.0 MPa or more,alternatively 1.5 MPa or more, alternatively 2.0 MPa or more,alternatively 2.5 MPa or more, alternatively 3.0 MPa or more,alternatively 3.5 MPa or more.

In another embodiment, the polymer blend described herein has a Shorehardness of 2A to 90A, preferably 15A to 70A (as measured by ISO 868).

In another embodiment, the polymer blend described herein has anultimate elongation (as measured by ISO 37) of 20% or more, preferably30% or more, more preferably 40% or more.

In another embodiment, the polymer blend described herein has acompression set (as measured by ISO 815A) of 90% or less, preferably 70%or less, more preferably 50% or less, more preferably 30% or less.

In another embodiment, the polymer blend described herein has a tensionset (as measured by ISO 2285) of 100% or less, preferably 80% or less,more preferably 60% or less, more preferably 20% or less.

In another embodiment, the polymer blend described herein has an oilswell (as measured by ASTM D471) of 500% or less, preferably 250% orless, more preferably 100% or less.

Additives

The heterogeneous polymer blend according to the invention mayoptionally contain reinforcing and non-reinforcing fillers,plasticizers, antioxidants, stabilizers, rubber processing oils,extender oils, lubricants, antiblocking agents, antistatic agents,waxes, foaming agents, pigments, flame retardants and other processingaids known in the rubber compounding art. Such additives may comprise upto about 70 weight percent, more preferably up to about 65 weightpercent, of the total composition. Suitable fillers and extendersinclude conventional inorganics such as calcium carbonate, clays,silica, talc, titanium dioxide, carbon black and the like. Suitablerubber processing oils generally are paraffinic, naphthenic or aromaticoils derived from petroleum fractions. The oils are selected from thoseordinarily used in conjunction with the specific rubber or rubbercomponent present in the composition.

The additives such as fillers and oils can be introduced into theheterogeneous polymer blend during the polymerization in either thefirst polymerization zone or the second polymerization zone. Theadditives can be added into the effluent from the second polymerizationzone and are preferably added into the polymer blend after removal ofsolvent or diluent through melt blending.

Additional polymers can also be added to form blends. In one or moreembodiments, the additional polymers include thermoplastic resins.Exemplary thermoplastic resins include crystalline polyolefins. Also,suitable thermoplastic resins may include copolymers of polyolefins withstyrene, such as a styrene-ethylene copolymer. In one or moreembodiments, the thermoplastic resins are formed by polymerizingethylene or α-olefins such as propylene, 1-butene, 1-hexene, 1-octene,2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene,5-methyl-1-hexene, and mixtures thereof. Copolymers of ethylene andpropylene and ethylene and propylene with another α-olefin such as1-butene, 1-hexene, 1-octene, 2-methyl-1-propene, 3-methyl-1-pentene,4-methyl-1-pentene, 5-methyl-1-hexene or mixtures thereof are alsocontemplated. Also suitable are homopolypropylene, as well as impact andrandom copolymers of propylene with ethylene or the higher α-olefins,described above, or with C₁₀-C₂₀ diolefins. Preferably, thehomopolypropylene has a melting point of at least 130° C., for exampleat least 140° C. and preferably less than or equal to 170° C., a heat offusion of at least 75 J/g, alternatively at least 80 J/g, as determinedby DSC analysis, and weight average molecular weight (Mw) of at least50,000, alternatively at least 100,000. Comonomer contents for thepropylene copolymers will typically be from 1 to about 30% by weight ofthe polymer, for example, see U.S. Pat. Nos. 6,268,438, 6,288,171, and6,245,856. Copolymers available under the tradename VISTAMAXX™(ExxonMobil) are specifically included. Blends or mixtures of two ormore polyolefin thermoplastics such as described herein, or with otherpolymeric modifiers, are also suitable in accordance with thisinvention. These homopolymers and copolymers may be synthesized by usingan appropriate polymerization technique known in the art such as, butnot limited to, the conventional Ziegler-Natta type polymerizations, andcatalysis employing single-site organometallic catalysts including, butnot limited to, metallocene catalysts.

In one or more embodiments, the polyene employed in the secondpolymerization step can be selected such that any pendant double bondsleft unreacted after production of the second polymer can undergo curingduring the finishing operation and thereby increase the crosslinkdensity of the rubber phase.

In one or more embodiments, during the finishing step curing agents canbe injected into the polymer finishing equipment to increase the curedensity of the continuous rubber phase. Exemplary curatives includephenolic resin cure systems, peroxide cure systems, andsilicon-containing cure systems.

In one or more embodiments, the phenolic resin curatives include thosedisclosed in U.S. Pat. Nos. 2,972,600, 3,287,440, 5,952,425 and6,437,030, and International Application No. PCT/US04/30518, the entirecontents of which are incorporated herein by reference.

Phenolic resin curatives can be referred to as resole resins, andinclude those resins made by the condensation of alkyl substitutedphenols or unsubstituted phenols with aldehydes, such as formaldehydes,in an alkaline medium or by condensation of bi-functionalphenoldialcohols. The alkyl substituents of the alkyl substitutedphenols may contain 1 to about 10 carbon atoms. Dimethylolphenols orphenolic resins, substituted in para-positions with alkyl groupscontaining 1 to about 10 carbon atoms are preferred. In one embodiment,a blend of octyl phenol and nonylphenol-formaldehyde resins areemployed. The blend may include from about 25 to about 40% by weightoctyl phenol and from about 75 to about 60% by weight nonylphenol(optionally from about 30 to about 35 weight percent octyl phenol andfrom about 70 to about 65 weight percent nonylphenol). In oneembodiment, the blend includes about 33% by weightoctylphenol-formaldehyde and about 67% by weight nonylphenolformaldehyde resin, where each of the octylphenol and nonylphenolinclude methylol groups. This blend can be solubilized in paraffinic oilat about 30% solids.

Useful phenolic resins may be obtained under the tradenames SP-1044,SP-1045 (Schenectady International; Schenectady, N.Y.), which arereferred to as alkylphenol-formaldehyde resins. SP-1045 is believed tobe an octylphenol-formaldehyde resin that contains methylol groups. TheSP-1044 and SP-1045 resins are believed to be essentially free ofhalogen substituents or residual halogen compounds. By essentially freeof halogen substituents, it is meant that the synthesis of the resinprovides for a non-halogenated resin that may only contain trace amountsof halogen containing compounds.

Alternatively, the phenolic resin can be used in combination with thehalogen source, such as stannous chloride, and a metal oxide or reducingcompound such as zinc oxide.

In one or more embodiments, useful peroxide curatives include organicperoxides. Examples of organic peroxides include, but are not limitedto, di-tert-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide,α,α-bis(tert-butylperoxy) diisopropyl benzene,2,5-dimethyl-2,5-di(t-butylperoxy)hexane (DBPH),1,1-di(tert-butylperoxy)-3,3,5-trimethyl cyclohexane,n-butyl-4-4-bis(tert-butylperoxy) valerate, benzoyl peroxide, lauroylperoxide, dilauroyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, and mixtures thereof. Also, diaryl peroxides, ketoneperoxides, peroxydicarbonates, peroxyesters, dialkyl peroxides,hydroperoxides, peroxyketals and mixtures thereof may be used. Usefulperoxides and their methods of use in dynamic vulcanization ofthermoplastic vulcanizates are disclosed in U.S. Pat. No. 5,656,693, theentire contents of which are incorporated herein by reference.

In one or more embodiments, the peroxide curatives are employed inconjunction with a coagent. Examples of coagents includetriallylcyanurate, triallyl isocyanurate, triallyl phosphate, sulfur,N-phenyl bis-maleamide, zinc diacrylate, zinc dimethacrylate, divinylbenzene, 1,2 polybutadiene, trimethylol propane trimethacrylate,tetramethylene glycol diacrylate, trifunctional acrylic ester,dipentaerythritolpentacrylate, polyfunctional acrylate, retardedcyclohexane dimethanol diacrylate ester, polyfunctional methacrylates,acrylate and methacrylate metal salts, oximer for e.g., quinone dioxime.In order to maximize the efficiency of peroxide/coagent crosslinking themixing and dynamic vulcanization are preferably carried out in anitrogen atmosphere.

In one or more embodiments, useful silicon-containing cure systemsinclude silicon hydride compounds having at least two SiH groups. It isbelieved that these compounds react with carbon-carbon double bonds ofunsaturated polymers in the presence of a hydrosilation catalyst.Silicon hydride compounds that are useful in practicing the presentinvention include, but are not limited to, methylhydrogen polysiloxanes,methylhydrogen dimethyl-siloxane copolymers, alkyl methyl polysiloxanes,bis(dimethylsilyl)alkanes, bis(dimethylsilyl)benzene, and mixturesthereof.

Useful catalysts for hydrosilation include, but are not limited to,peroxide catalysts and catalysts including transition metals of GroupVIII. These metals include, but are not limited to, palladium, rhodium,and platinum, as well as complexes of these metals. For a furtherdiscussion of the use of hydrosilation to cure thermoplasticvulcanizates, reference can be made to U.S. Pat. No. 5,936,028, which isincorporated herein by reference. In one or more embodiments, asilicon-containing curative can be employed to cure an elastomericcopolymer including units deriving from 5-vinyl-2-norbornene.

In one or more embodiments, curatives that are useful for curing theinventive polymer blend include those described in U.S. Pat. Nos.5,013,793, 5,100,947, 5,021,500, 4,978,714, and 4,810,752, which areincorporated herein by reference.

Uses of the Polymer Blends

Despite the fact that the elastomer is at least partially cross-linked,the compositions of this invention can be processed and reprocessed byconventional plastic processing techniques such as extrusion, injectionmolding, and compression molding. The elastomer within theseheterogeneous blends is usually in the form of finely-divided particles,even though they are visually in the continuous morphology phase in thesolid-state.

The heterogeneous polymer blends described herein may be shaped intodesirable end use articles by any suitable means known in the art. Theyare particularly useful for making articles by blow molding, extrusion,injection molding, thermoforming, gas foaming, elasto-welding andcompression molding techniques.

Thermoforming is a process of forming at least one pliable plastic sheetinto a desired shape. An embodiment of a thermoforming sequence isdescribed, however this should not be construed as limiting thethermoforming methods useful with the compositions of this invention.First, an extrudate film of the composition of this invention (and anyother layers or materials) is placed on a shuttle rack to hold it duringheating. The shuttle rack indexes into the oven which pre-heats the filmbefore forming. Once the film is heated, the shuttle rack indexes backto the forming tool. The film is then vacuumed onto the forming tool tohold it in place and the forming tool is closed. The forming tool can beeither “male” or “female” type tools. The tool stays closed to cool thefilm and the tool is then opened. The shaped laminate is then removedfrom the tool.

Thermoforming is accomplished by vacuum, positive air pressure,plug-assisted vacuum forming, or combinations and variations of these,once the sheet of material reaches thermoforming temperatures, typicallyof from 140° C. to 185° C. or higher. A pre-stretched bubble step isused, especially on large parts, to improve material distribution. Inone embodiment, an articulating rack lifts the heated laminate towards amale forming tool, assisted by the application of a vacuum from orificesin the male forming tool. Once the laminate is firmly formed about themale forming tool, the thermoformed shaped laminate is then cooled,typically by blowers. Plug-assisted forming is generally used for small,deep drawn parts. Plug material, design, and timing can be critical tooptimization of the process. Plugs made from insulating foam avoidpremature quenching of the plastic. The plug shape is usually similar tothe mold cavity, but smaller and without part detail. A round plugbottom will usually promote even material distribution and uniformside-wall thickness.

The shaped laminate is then cooled in the mold. Sufficient cooling tomaintain a mold temperature of 30° C. to 65° C. is desirable. The partis below 90° C. to 100° C. before ejection in one embodiment. For thegood behavior in thermoforming, the lowest melt flow rate polymers aredesirable. The shaped laminate is then trimmed of excess laminatematerial.

Blow molding is another suitable forming means, which includes injectionblow molding, multi-layer blow molding, extrusion blow molding, andstretch blow molding, and is especially suitable for substantiallyclosed or hollow objects, such as, for example, gas tanks and otherfluid containers. Blow molding is described in more detail in, forexample, CONCISE ENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING 90-92(Jacqueline I. Kroschwitz, ed., John Wiley & Sons 1990).

In yet another embodiment of the formation and shaping process, profileco-extrusion can be used. The profile co-extrusion process parametersare as above for the blow molding process, except the die temperatures(dual zone top and bottom) range from 150° C. to 235° C., the feedblocks are from 90° C. to 250° C., and the water cooling tanktemperatures are from 10° C. to 40° C.

One embodiment of an injection molding process is described as follows.The shaped laminate is placed into the injection molding tool. The moldis closed and the substrate material is injected into the mold. Thesubstrate material has a melt temperature between 200° C. and 300° C.,such as between 215° C. and 250° C. and is injected into the mold at aninjection speed of between 2 and 10 seconds. After injection, thematerial is packed or held at a predetermined time and pressure to makethe part dimensionally and aesthetically correct. Typical time periodsare from 5 to 25 seconds and pressures from 1,380 kPa to 10,400 kPa. Themold is cooled between 10° C. and 70° C. to cool the substrate. Thetemperature will depend on the desired gloss and appearance desired.Typical cooling time is from 10 to 30 seconds, depending on part on thethickness. Finally, the mold is opened and the shaped composite articleejected.

Likewise, molded articles may be fabricated by injecting molten polymerinto a mold that shapes and solidifies the molten polymer into desirablegeometry and thickness of molded articles. Sheet may be made either byextruding a substantially flat profile from a die, onto a chill roll, oralternatively by calendaring. Sheet will generally be considered to havea thickness of from 10 mils to 100 mils (254 μm to 2540 μm), althoughsheet may be substantially thicker. Tubing or pipe may be obtained byprofile extrusion for uses in medical, potable water, land drainageapplications or the like. The profile extrusion process involves theextrusion of molten polymer through a die. The extruded tubing or pipeis then solidified by chill water or cooling air into a continuousextruded articles. The tubing will generally be in the range of from0.31 cm to 2.54 cm in outside diameter, and have a wall thickness of inthe range of from 254 cm to 0.5 cm. The pipe will generally be in therange of from 2.54 cm to 254 cm in outside diameter, and have a wallthickness of in the range of from 0.5 cm to 15 cm. Sheet made from theproducts of an embodiment of a version of the present invention may beused to form containers. Such containers may be formed by thermoforming,solid phase pressure forming, stamping and other shaping techniques.Sheets may also be formed to cover floors or walls or other surfaces.

In an embodiment of the thermoforming process, the oven temperature isbetween 160° C. and 195° C., the time in the oven between 10 and 20seconds, and the die temperature, typically a male die, between 10° C.and 71° C. The final thickness of the cooled (room temperature), shapedlaminate is from 10 μm to 6000 μm in one embodiment, from 200 μm to 6000μm in another embodiment, and from 250 μm to 3000 μm in yet anotherembodiment, and from 500 μm to 1550 μm in yet another embodiment, adesirable range being any combination of any upper thickness limit withany lower thickness limit.

In an embodiment of the injection molding process, wherein a substratematerial is injection molded into a tool including the shaped laminate,the melt temperature of the substrate material is between 230° C. and255° C. in one embodiment, and between 235° C. and 250° C. in anotherembodiment, the fill time from 2 to 10 seconds in one embodiment, from 2to 8 seconds in another embodiment, and a tool temperature of from 25°C. to 65° C. in one embodiment, and from 27° C. and 60° C. in anotherembodiment. In a desirable embodiment, the substrate material is at atemperature that is hot enough to melt any tie-layer material or backinglayer to achieve adhesion between the layers.

In yet another embodiment of the invention, the compositions of thisinvention may be secured to a substrate material using a blow moldingoperation. Blow molding is particularly useful in such applications asfor making closed articles such as fuel tanks and other fluidcontainers, playground equipment, outdoor furniture and small enclosedstructures. In one embodiment of this process, Compositions of thisinvention are extruded through a multi-layer head, followed by placementof the uncooled laminate into a parison in the mold. The mold, witheither male or female patterns inside, is then closed and air is blowninto the mold to form the part.

It will be understood by those skilled in the art that the stepsoutlined above may be varied, depending upon the desired result. Forexample, an extruded sheet of the compositions of this invention may bedirectly thermoformed or blow molded without cooling, thus skipping acooling step. Other parameters may be varied as well in order to achievea finished composite article having desirable features.

The thermoplastic elastomer blends of this invention are useful formaking a variety of articles such as weather seals, hoses, belts,gaskets, moldings, boots, elastic fibers and like articles. Foamedend-use articles are also envisioned. More specifically, the blends ofthe invention are particularly useful for making vehicle parts, such asbut not limited to, weather seals, brake parts including, but notlimited to cups, coupling disks, diaphragm cups, boots such as constantvelocity joints and rack and pinion joints, tubing, sealing gaskets,parts of hydraulically or pneumatically operated apparatus, o-rings,pistons, valves, valve seats, valve guides, and other elastomericpolymer based parts or elastomeric polymers combined with othermaterials such as metal, plastic combination materials which will beknown to those of ordinary skill in the art. Also contemplated aretransmission belts including V-belts, toothed belts with truncated ribscontaining fabric faced V's, ground short fiber reinforced Vs or moldedgum with short fiber flocked V's. The cross section of such belts andtheir number of ribs may vary with the final use of the belt, the typeof market and the power to transmit. They also can be flat made oftextile fabric reinforcement with frictioned outside faces. Vehiclescontemplated where these parts will find application include, but arenot limited to passenger autos, motorcycles, trucks, boats and othervehicular conveyances.

In another embodiment, this invention relates to:

-   1. A heterogeneous polymer blend comprising:    -   (a) a dispersed phase comprising a thermoplastic first polymer        having a crystallinity of at least 30%; and    -   (b) a continuous phase comprising a second polymer different        from the first polymer, the second polymer having a        crystallinity of less than 20% and being at least partially        cross-linked.-   2. The polymer blend of paragraph 1 wherein said second polymer is    at least partially cross-linked such that at least a fraction of    said continuous phase is insoluble in xylene.-   3. The polymer blend of paragraph 2 wherein said fraction insoluble    in xylene comprises at least 5% by weight, preferably at least 20%    by weight, of said continuous phase.-   4. The polymer blend of any of paragraphs 1 to 3 wherein said    dispersed phase comprises particles of said thermoplastic first    polymer having an average particle size less than 10 microns,    preferably less than 5 microns.-   5. The polymer blend of any of paragraphs 1 to 4 wherein said    dispersed phase comprises less than 50% by weight, preferably less    than 30% by weight, of the total heterogeneous polymer blend.-   6. The polymer blend of any of paragraphs 1 to 5 wherein said    thermoplastic first polymer is a homopolymer of a C₂ to C₂₀ olefin.-   7. The polymer blend of any of paragraphs 1 to 5 wherein said    thermoplastic first polymer is a copolymer of a C₂ to C₂₀ olefin    with less than 15 wt % of at least one comonomer.-   8. The polymer blend of any of paragraphs 1 to 7 wherein said    thermoplastic first polymer comprises a polymer of propylene.-   9. The polymer blend of of any of paragraphs 1 to 8 wherein the    second polymer is produced from a plurality of comonomers comprising    at least one C₃ to C₂₀ olefin and at least one polyene.-   10. The polymer blend of paragraph 9 wherein said at least one    polyene has at least two polymerizable unsaturated groups.-   11. The polymer blend of paragraph 9 or paragraph 10 wherein said    plurality of comonomers comprise propylene and ethylene.-   12. The polymer blend of any of paragraphs 1 to 11 wherein the blend    is substantially free of processing oil and curative.-   13. The polymer blend of any of paragraphs 1 to 11 wherein said    continuous phase comprises a curative such that no more than about    50 wt % of the second polymer is extractable in cyclohexane at 23°    C.-   14. The polymer blend of paragraph 13 wherein said curative is    selected from a phenolic resin, a peroxide and a silicon-containing    curative.-   15. The polymer blend of any of paragraphs 1 to 14 and further    including one or more additives selected from fillers, extenders,    plasticizers, antioxidants, stabilizers, oils, lubricants, and    additional polymers.-   16. A process for producing the polymer blend of any of paragraphs 1    to 15, the process comprising:    -   (i) polymerizing at least one first monomer to produce the        thermoplastic first polymer;    -   (ii) contacting at least part of said first polymer with at        least one second monomer and at least one polyene under        conditions sufficient to polymerize said second monomer to        produce, and simultaneously cross-link, said second polymer as        finely divided particles.-   17. The process of paragraph 16 wherein said polymerizing (i) is    conducted in the presence of a catalyst and said contacting (ii) is    conducted in the presence of the same catalyst.-   18. The process of paragraph 16 wherein said polymerizing (i) is    conducted in the presence of a first catalyst and said    contacting (ii) is conducted in the presence of a second catalyst    different from the first catalyst.-   19. The process of any one of paragraphs 16 to 18 wherein the first    polymer produced in said polymerizing (i) has at least 0.01%    terminal unsaturation.-   20. The process of any one of paragraphs 16 to 19 wherein the    product of said contacting (ii) is subjected to an additional curing    step to further cross-link said second polymer.-   21. The process of paragraph 20 wherein, following said curing step,    at least 70 wt % of said second polymer is insoluble in xylene.-   22. The process of paragraph 20 or paragraph 21 wherein said curing    step comprises dynamic vulcanization.

The invention will now be more particularly described with reference tothe Examples and the accompanying drawings.

In the Examples, molecular weights (number average molecular weight(Mn), weight average molecular weight (Mw), and z-average molecularweight (Mz)) were determined using a Waters 150 Size ExclusionChromatograph (SEC) equipped with a differential refractive indexdetector (DRI), an online low angle light scattering (LALLS) detectorand a viscometer (VIS). The details of these detectors as well as theircalibrations have been described by, for example, T. Sun, P. Brant, R.R. Chance, and W. W. Graessley, in Macromolecules, Volume 34, Number 19,6812-6820, (2001), incorporated herein by reference. Solvent for the SECexperiment was prepared by adding 6 grams of butylated hydroxy toluene(BHT) as an antioxidant to a 4 liter bottle of 1,2,4 trichlorobenzene(TCB) (Aldrich Reagent grade) and waiting for the BHT to solubilize. TheTCB mixture was then filtered through a 0.7 micron glass pre-filter andsubsequently through a 0.1 micron Teflon filter. There was an additionalonline 0.7 micron glass pre-filter/0.22 micron Teflon filter assemblybetween the high pressure pump and SEC columns. The TCB was thendegassed with an online degasser (Phenomenex, Model DG-4000) beforeentering the SEC. Polymer solutions were prepared by placing dry polymerin a glass container, adding the desired amount of TCB, then heating themixture at 160° C. with continuous agitation for about 2 hours. Allquantities were measured gravimetrically. The TCB densities used toexpress the polymer concentration in mass/volume units were 1.463 g/mlat room temperature and 1.324 g/ml at 135° C. The injectionconcentration ranged from 1.0 to 2.0 mg/ml, with lower concentrationsbeing used for higher molecular weight samples.

The branching index in the Examples was measured using SEC with anon-line viscometer (SEC-VIS) and is reported as g′ at each molecularweight in the SEC trace. The branching index g′ is defined as:$g^{\prime} = \frac{\eta_{b}}{\eta_{l}}$where η_(b) is the intrinsic viscosity of the branched polymer and η₁ isthe intrinsic viscosity of a linear polymer of the sameviscosity-averaged molecular weight (M_(v)) as the branched polymer.η₁=KM_(v) ^(α), K and α were measured values for linear polymers andshould be obtained on the same SEC-DRI-LS-VIS instrument as the one usedfor branching index measurement. For polypropylene samples presented inthis invention, K=0.0002288 and α=0.705 were used. The SEC-DRI-LS-VISmethod obviates the need to correct for polydispersities, since theintrinsic viscosity and the molecular weight were measured at individualelution volumes, which arguably contain narrowly dispersed polymer.Linear polymers selected as standards for comparison should be of thesame viscosity average molecular weight, monomer content and compositiondistribution. Linear character for polymer containing C2 to C10 monomersis confirmed by Carbon-13 NMR using the method of Randall (Rev.Macromol. Chem. Phys., C29 (2&3), p. 285-297). Linear character for C11and above monomers is confirmed by GPC analysis using a MALLS detector.For example, for a copolymer of propylene, the NMR should not indicatebranching greater than that of the co-monomer (i.e. if the comonomer isbutene, branches of greater than two carbons should not be present). Fora homopolymer of propylene, the GPC should not show branches of morethan one carbon atom. When a linear standard is desired for a polymerwhere the comonomer is C9 or more, one can refer to T. Sun, P. Brant, R.R. Chance, and W. W. Graessley, Macromolecules, Volume 34, Number 19,6812-6820, (2001) for protocols on determining standards for thosepolymers. In the case of syndiotactic polymers, the standard should havea comparable amount of syndiotacticty as measured by Carbon 13 NMR. Theviscosity averaged g′ was calculated using the following equation:$g_{vis}^{\prime} = \frac{\sum{C_{i}\left\lbrack \eta_{i} \right\rbrack}_{b}}{\sum{C_{i}K\quad M_{i}^{\alpha}}}$where C_(i) is the polymer concentration in the slice i in the polymerpeak, and [η_(i)]_(b) is the viscosity of the branched polymer in slicei of the polymer peak, and M_(i) is the weight averaged molecular weightin slice i of the polymer peak measured by light scattering, K and α areas defined above.

Peak melting point (Tm) and peak crystallization temperature (Tc) weredetermined using the following procedure according to ASTM E 794-85.Crystallinity was calculated using heat of fusion determined using ASTMD 3417-99. Differential scanning calorimetric (DSC) data were obtainedusing a TA Instruments model Q100 machine or a Perkin-Elmer DSC-7.Samples weighing approximately 5-10 mg were sealed in aluminum samplepans. The DSC data were recorded by first heating a sample from roomtemperature to 200° C. at a rate of 10° C./minute (1st melt). Then thesample was kept at 200° C. for 5 minutes before ramping at 10° C./minuteto −100° C., followed by isothermal for 5 minutes at −100° C. thenheating to 200° C. at a rate of 10° C./minute (2nd melt). Both the firstand second cycle thermal events were recorded. The peak meltingtemperature and heat of fusion reported in the examples were obtainedfrom the second melt. Areas under the melting curves were measured andused to determine the heat of fusion and the degree of crystallinity.The percent crystallinity is calculated using the formula, [area underthe curve (Joules/gram)/B (Joules/gram)]*100, where B is the heat offusion for the homopolymer of the major monomer component. These valuesfor B were obtained from the Polymer Handbook, Fourth Edition, publishedby John Wiley and Sons, New York 1999. A value of 189 J/g (B) was usedas the heat of fusion for 100% crystalline polypropylene. A value of 290J/g is used for the heat of fusion for 100% crystalline polyethylene.For polymers displaying multiple cooling and melting peaks, all the peakcrystallization temperatures and peaks melting temperatures werereported. The heat of fusion for each melting peak was calculatedindividually.

The glass transition temperature (Tg) was measured by ASTM E 1356 usinga TA Instruments model Q100 machine.

Morphology data were obtained using an Atomic Force Microscope (AFM) intapping phase. All specimens were analyzed within 8 hours aftercryofacing to prevent specimen relaxation. During cryofacing, thespecimens were cooled to −130° C. and cut with diamond knives in aReichert cryogenic microtome. They were then stored in a dissector underflowing dry nitrogen gas to warm up to ambient temperatures withoutcondensation being formed. Finally, the faced specimens were mounted ina miniature steel vise for AFM analysis. The AFM measurements wereperformed in air on a NanoScope Dimension 3000 scanning probe microscope(Digital Instrument) using a rectangular 225-mm Si cantilever. Thestiffness of the cantilever was ˜4 N/m with a resonance frequency of 70kHz. The free vibration amplitude was high, in the range of 80 nm to 100nm, with a RMS setting of 3.8 volts. While the set point ratio wasmaintained at a value equal to or lower than 0.5, the contact set pointwas adjusted routinely to ensure repulsive contacts with positive phaseshifts. The cantilever was running at or slightly below its resonancefrequency.

AFM phase images of all specimens were converted into a TIFF format andprocessed using PHOTOSHOP (Adobe Systems, Inc.). The image processingtool kit (Reindeer Games, Inc.) was applied for image measurements.Results of image measurements were written into a text file forsubsequent data processing using EXCEL (Microsoft) or MATLAB (MathWorks,Inc.) for computing sizes/shapes of dispersed phases, co-continuityfactor of co-continuous phases, or nearest-neighbor inter-particledistances.

Transmission Electron Microscopy (TEM) was used to study details of theinterface between the ethylene/propylene/diene rubber and thesemi-crystalline polypropylene phases. The instrument used was the JEOL2000FX microscope. A heavy metal staining technique was employed toprovide contrast to delineate the details of the sample morphology.Ruthenium tetroxide provides excellent contrast between amorphous andcrystalline regions and was used. Lower density and amorphous polymerstake up more stain than do higher density and more crystallinecomponents. Thus heavily stained components appear darker in TEMamplitude contrast images whereas less heavily stained materials appearlighter. The TEM analytical method used involved:

-   -   Setting the orientation of the plane of analysis. Typically the        MD-ND (machine direction/normal direction) plane is preferred        for samples that may be oriented in the machine direction.    -   Creating a deformation-free face through the bulk polymer sample        using a cryomicrotome.    -   Staining with ruthenium tetroxide vapor for about 8 hours.    -   Cutting and collecting ultrathin (about 100 nm) sections from        the stained face using an ultramicrotome. The cutting is done        using a diamond knife. Sections are floated onto TEM grids.    -   Loading sections into the TEM for examination at the appropriate        accelerating voltage (typically 160 to 200 kV).    -   Examining the sections to determine level of sampling needed.    -   Acquiring digital images using appropriate vendor software.

The ethylene content of ethylene/propylene copolymers was determinedusing FTIR according to the following technique. A thin homogeneous filmof polymer, pressed at a temperature of about 150° C., was mounted on aPerkin Elmer Spectrum 2000 infrared spectrophotometer. A fill spectrumof the sample from 600 cm⁻¹ to 4000 cm⁻¹ was recorded and the area underpropylene band at ˜1165 cm⁻¹ and the area of ethylene band at ˜732 cm⁻¹in the spectrum were calculated. The baseline integration range for themethylene rocking band is nominally from 695 cm⁻¹ to the minimum between745 and 775 cm⁻¹. For the polypropylene band the baseline andintegration range is nominally from 1195 to 1126 cm⁻¹ . The ethylenecontent in wt. % was calculated according to the following equation:ethylene content (wt. %)=72.698-86.495X+13.696X ²where X=AR/(AR+1) and AR is the ratio of the area for the peak at ˜1165cm⁻¹ to the area of the peak at ˜732 cm⁻¹.

Solvent extraction was used to isolate the different polymer species ofthe in-reactor polymer blends. The fractionations were carried out in atwo-step successive solvent extraction when the polymer blend does notcontain any oil: one involves cyclohexane extraction, the other xyleneSoxhlet extraction. In the cyclohexane solvent extraction, about 0.3gram of polymer was placed in about 60 ml of cyclohexane to isolate theuncured and lightly branched elastomeric components of the polymerblend. The mixture was continuously stirred at room temperature forabout 48 hours. The soluble fraction (referred as cyclohexane solubles)was separated from the insoluble material (referred as cyclohexaneinsolubles) using filtration under vacuum. The insoluble material wasthen subjected to the xylene soxhlet extraction procedure. In this step,the insoluble material from the room temperature cyclohexane extractionwas first extracted for about 24 hours with xylene. The xylene insolubleportion (referred as xylene insolubles) was recovered by filtration andis the extract containing the at least partially cross-linked secondpolymer. The remaining portion was cooled down to room temperature andretained in a glass container for 24 hours for precipitation. Theprecipitated component (referred as xylene precipitate) was recoveredthrough filtration and the soluble component (referred as xylenesoluble) was recovered by evaporating the xylene solvent. The xyleneprecipitate fraction is where the thermoplastic crystalline componentresides. In the case of blends containing paraffinic oil plasticizer andthe like, another Soxhlet solvent extraction step was performed on thesample for 24 hours to isolate the oil from the blend before thecyclohexane extraction and xylene Soxhlet extraction using an azeoptropeof acetone and cyclohexane in the ratio 2:1 by volume.

In order to measure the physical properties of the polymer blends,samples were first mixed in a Brabender melt mixer with ˜45 mL mixinghead. The polymer was stabilized with antioxidant during mixing in theBrabender. The Brabender was operated at 100 rpm and at temperature of180° C. Mixing time at temperature was 5-10 minutes, after which thesample was removed from the mixing chamber. The homogenized samples weremolded under compression into film on a Carver hydraulic press foranalysis. About 7 grams of the homogenized polymer were molded betweenbrass platens lined with Teflon™ coated aluminum foil. A 0.033 inch(0.08 cm) thick chase with a square opening 4 inch×4 inch (10.2×10.2 cm)was used to control sample thickness. After one minute of preheat at170° C. or 180° C., under minimal pressure, the hydraulic load wasgradually increased to 10,000 to 15,000 lbs, at which it was held forthree minutes. Subsequently the sample and molding plates were cooledfor three minutes under 10,000 to 15,000 lbs load between thewater-cooled platens of the press. Plaques were allowed to equilibrateat room temperature for a minimum of 24 hours prior to physical propertytesting.

Loss Modulus (E″), Storage Modulus (E′) and β relaxation were measuredby dynamic mechanical thermal analysis (DMTA). The instrument used wasthe RSA II, Rheometrics Solid Analyzer II from TA Instruments, NewCastle, Del. The instrument was operated in tension mode and used moldedrectangular samples. Sample conditions were: 0.1% strain, 1 Hzfrequency, and 2° C. per minute heating rate, covering the temperaturerange from −135° C. to the melting point of the sample. Samples weremolded at about 200° C. Typical sample dimensions were 23 mm length×6.4mm width x thickness between 0.25 mm and 0.7 mm, depending on thesample. Tan δ is the ratio of E″/E′. The output of these DMTAexperiments is the storage modulus (E′) and loss modulus (E″). Thestorage modulus measures the elastic response or the ability of thematerial to store energy, and the loss modulus measures the viscousresponse or the ability of the material to dissipate energy. The ratioof E″/E′ (=tan δ) gives a measure of the damping ability of thematerial. Energy dissipation mechanisms (i.e., relaxation modes) show upas peaks in tan δ, and are associated with a drop in E′ as a function oftemperature. The uncertainty associated with reported values of E′ isexpected to be on the order of ±10%, due to variability introduced bythe molding process.

Shore hardness was determined according to ISO 868 at 23° C. using aDurometer.

Stress-strain properties such as ultimate tensile strength, ultimateelongation, and 100% modulus were measured on 2 mm thick compressionmolded plaques at 23° C. by using an Instron testing machine accordingto ISO 37.

Compression set test was measured according to ISO 815A.

Tension set was measured according to ISO 2285.

Oil swell (oil gain) was determined after soaking a die-cut sample fromcompression molded plaque in IRM No. 3 fluid for 24 hours at 125° C.according to ASTM D 471.

LCR viscosity was measured using Laboratory Capillary Rheometeraccording to ASTM D 3835-02 including that the viscosity is measuredusing a Dynisco Capillary rheometer at 30:1 L/D (length/diameter) ratio,a shear rate of 1200 l/s and a temperature of 204° C. The entrance angleof the laboratory capillary rheometer is 180°, barrel diameter is 9.55mm. The heat soak time is 6 minutes.

EXAMPLE 1

A polymer blend was produced in a two-stage polymerization reaction bypolymerizing propylene in a first stage to make homopolymer, andcopolymerizing propylene and ethylene as well as a diene cross-linkingagent in a second stage in the presence of the homopolyrner produced inthe first stage. The polymerization was carried out in a 2-literautoclave reactor equipped with a stirrer, an external water/steamjacket for temperature control, a regulated supply of dry nitrogen,ethylene, and propylene, and a septum inlet for introduction of othersolvents, catalysts and scavenger solutions. The reactor was firstwashed using hot toluene and then dried and degassed thoroughly prior touse. All the solvents and monomers were purified by passing through a1-liter basic alumina column activated at 600° C., followed by a columnof molecular sieves activated at 600° C. or Selexsorb CD column prior totransferring into the reactor.

In the first stage of polymerization, 3 ml of tri-n-octylaluminum (TNOA)(25 wt. % in hexane, Sigma Aldrich) solution was first added to thereactor. In succession, solvent (diluent) and propylene were added intothe reactor. All of these were conducted at room temperature. Themixture was then stirred and heated to the desired temperature for thefirst polymerization stage. Then the catalyst solution was cannulatedinto the reactor using additional propylene. The first stage ofpolymerization was ended when the desired amount of polypropylene wasproduced. Thereafter, the reactor was heated up to the desiredtemperature of the second polymerization stage. About 6˜12 ml of air wasinjected into the reactor with about 100 ml of additional solvent topartially deactivate the catalyst used in the first stage ofpolymerization. The reaction medium was kept under proper mixing forabout 8 minutes to allow good catalyst-air contact prior to second stageof polymerization. The reactor was then pressurized to about 400 psigwith ethylene. Then, in succession, diene, additional scavenger (TNOA orTEAL) and the second catalyst solution were added into the reactor.Additional ethylene was fed into the reactor, and the ethylene was fedon demand to maintain a relatively constant reactor pressure during thesecond polymerization reaction. The second polymerization reaction wasterminated when desired amount of rubber was produced. Thereafter, thereactor was cooled down and unreacted monomer and solvent (diluent) werevented to the atmosphere. The resulting mixture, containing mostlysolvent, polymer and unreacted monomers, was collected in a collectionbox and first air-dried in a hood to evaporate most of the solvent, andthen dried in a vacuum oven at a temperature of about 90° C. for about12 hours.

1,9-decadiene was used as the diene cross-linking agent in the secondpolymerization stage. The 1,9-decadiene was obtained from Sigma-Aldrichand was purified by first passing through an alumina column activated athigh temperature under nitrogen, followed by a molecular sieve activatedat high temperature under nitrogen.

Rac-dimethylsilyl bis(2-methyl-4-phenylindenyl) zirconium dimethylcatalyst (Catalyst A) was used in the first stage to producepolypropylene and [di(p-triethylsilylphenyl) methylene](cyclopentadienyl) (3,8-di-t-butylfluorenyl)hafnium dimethyl catalyst(Catalyst B) (obtained from Albemarle) was used in the second stage toproduce ethylene propylene diene rubber. Both catalysts werepreactivated by dimethylanilinum tetrakis(heptafluoro-2-naphthyl) borateat a molar ratio of 1:1 in toluene. Details of the experimentalconditions, catalysts employed and the properties of the resultantpolymer blends are listed in Table 1A below. TABLE 1A Polymerization inStage 1 Reaction temperature (° C.) 75 Amount of catalyst A (mg) 0.5Propylene #1 (ml) 700 Toluene (ml) 500 TNOA (25 wt. %) (ml) 3 Reactiontime1 (min) 7 Polymerization in Stage 2 Reaction temperature (° C.) 75Amount of catalyst B (mg) 1 Propylene2 (ml) Ethylene head pressure (psi)230 1,9 decadiene (ml) 50 Toluene (ml) 300 TNOA (25 wt %) (ml) 5Reaction time2 (min) 10 Yield (g) 88 Tm (° C.) 154.16 Tc (° C.) 102.31Heat of fusion (J/g) 10.6 Tg (° C.) −48.11 Ethylene content (wt %) 34.3Xylene precipitate (wt %) 11.66 Xylene insolubles (wt %) 55.11 Xylenesolubles (wt %) 21.33 Cyclohexane solubles (wt %) 9.81 Degree ofcross-link (%) 62.4

The in-reactor produced polymer blend produced in Example 1 wassubjected to solvent extraction. The amount of each fraction is listedin Table 1A. The amount of each fraction is listed as the weight percentof total in-reactor produced polymer blend. Degree of cross-linking isdefined as:${{Degree}\quad{of}\quad{cross}\text{-}{link}} = {\frac{{Percent}\quad{of}\quad{xylene}\quad{insoluble}}{100 - {{percent}\quad{of}\quad{xylene}\quad{precipitate}}} \times 100}$

The degree of cross-link is also referred as to the percent of thesecond polymer insoluble in xylene. Percent of the second polymerextractable in cyclohexane is defined as$\frac{{Percent}\quad{of}\quad{cyclohexane}{\quad\quad}{soluble}}{100 - {{percent}\quad{of}\quad{xylene}\quad{precipitate}}} \times 100$

The Tg value shown in the Table 1A above refers to the elastomercomponent of the reactor-produced blend. The value provides anindication of the amorphous nature of the elastomer component. The Tg ofthe polypropylene component—located primarily in the xylene precipitatefraction—is generally about 0° C., typical for semi-crystallinepropylene homopolymers.

The morphology of the blend produced in Example 1 was examined using AFMaccording to the procedure described above and the results are shown inFIG. 1.

A sample of the polymer blend produced in Example 1 was melt mixed in aBrabender mixer and molded under compression into plaques, and testedfor thermoplastic elastomer applications. Further samples of the polymerblend produced in Example 1 were further cured by dynamic vulcanization.The vulcanization was effected by conventional techniques within aBrabender mixer along with the other added ingredients listed in Table1B. Silicon hydride DC 25804 (1.97%) was obtained from Dow Corning. Thesilicon hydride was a polysiloxane with silicon hydride functionality.Platinum catalyst mixture (PC085) (2.63%) was obtained from UnitedChemical Technologies Inc. The catalyst mixture included 0.0055 parts byweight platinum catalyst and 2.49 parts by weight mineral oil. Zincoxide was obtained from Zinc Corporation of America and paraffinic oilParalux 6001R was obtained from Chevron Oil Corporation. The performancedata obtained according to the procedures described above are listed inTable 1B. TABLE 1B Polymer (wt. %) 100 69.93 65.79 Paralux 6001R (wt. %)0 30.07 28.29 SiH-DC25804 (wt. %) 0 0 1.97 Pt Catalyst (PC 085) (wt. %)0 0 2.63 Zinc oxide (wt. %) 0 0 1.32 Hardness 60A 38A 41A Ultimatetension strength (psi) 712 422.4 345.9 Ultimate elongation (%) 118 128141.9 100% Modulus (psi) 684 327.6 233.1 LCR viscosity 12001/s (Pa-s) NA331.6 103.5 Tension set (%) 8.25 2.75 4.75 Compression set, 70° C./22Hrs (%) 22.7 22.3 29.2 Weight gain, 121° C./24 hrs (%) 375.5 332 205

EXAMPLE 2

This sample was produced in a 2-liter autoclave reactor following thesame procedure as that used in Example 1, except that no air injectionwas used in between Stage 1 and Stage 2 polymerization. The samecatalyst was used in both stages of polymerization, and the catalyst waspreactivated with N,N-dimethylanilinium tetrakis (pentafluorophenyl)borate (obtained from Albemarle) at a molar ratio of about 1:1 intoluene. Triisobutyl aluminum (TIBAL) (25 wt % in toluene, purchasedfrom Sigma-Aldrich) was used as a scavenger. The detailed reactionconditions and polymer properties are listed in Table 2A. TABLE 2APolymerization in Stage 1 Reaction temperature (° C.) 70 Amount ofcatalyst A (mg) 0.5 Propylene #1 (ml) 500 Hexane (ml) 700 TIBAL (25 wt %in Toluene) (ml) 4 Reaction time1 (min) 4 Polymerization in Stage 2Reaction temperature (° C.) 85 Amount of catalyst A (mg) 0.72 Ethylenehead pressure (psi) 200 1,9 decadiene (ml) 4 Hexane (ml) 100 Reactiontime2 (min) 28 Yield (g) 131.2 Tm (° C.) 158.45 Tc (° C.) 107.36 Heat offusion (J/g) 11.35 Ethylene content (wt %) 24.7 Xylene precipitate (wt%) 14.1 Xylene insolubles (wt %) 29.6 Xylene solubles (wt %) 6Cyclohexane solubles (wt %) 50.22 Degree of cross-link (%) 34.5

The in-reactor produced polymer blend of Example 2 was subjected solventextraction using the procedure described above. The amount of eachextracted fraction is expressed as weight percent of total polymerblend, and is listed in Table 2A. The morphology of the blend producedin Example 2 was examined using AFM according to the procedure describedabove and the results are shown in FIG. 2.

A sample of the polymer blend produced in Example 2 was melt mixed in aBrabender mixer and molded under compression into plaques, and testedfor thermoplastic elastomer applications. A further sample of thepolymer blend produced in Example 2 was compounded with a processing oil(Paralux 6001R). The performance data obtained using the proceduredescribed above are listed in Table 2B. TABLE 2B Polymer (wt. %) 100 70Paralux 6001R (wt. %) 0 30 Hardness 37A 12A Ultimate tension strength(psi) 412 416 Ultimate elongation (%) 330 522 100% Modulus (psi) 250 79LCR viscosity 12001/s (Pa-s) 263.8 49.1 Tension set (%) 14.75 9.25Compression set, 70° C./22 Hrs (%) 60.46 55.24 Weight gain, 121° C./24hrs (%) 357.7 558.5All documents described herein are incorporated by reference herein,including any priority documents and/or testing procedures to the extentthey are not inconsistent with this text. While there have beendescribed what are presently believed to be the preferred embodiments ofthe present invention, those skilled in the art will realize that otherand further embodiments can be made without departing from the spirit ofthe invention, and is intended to include all such further modificationsand changes as come within the true scope of the claims set forthherein. Likewise, the term “comprising” is considered synonymous withthe term “including” for purposes of Australian law.

2. A heterogeneous polymer blend comprising: (a) a dispersed phasecomprising a thermoplastic first polymer having a crystallinity of atleast 30%; and (b) a continuous phase comprising a second polymerdifferent from the first polymer, the second polymer having acrystallinity of less than 20% and being at least partiallycross-linked.
 3. The polymer blend of claim 1 wherein said secondpolymer is at least partially cross-linked such that at least a fractionof said continuous phase is insoluble in xylene.
 4. The polymer blend ofclaim 2 wherein said fraction insoluble in xylene comprises at least 5%by weight of said continuous phase.
 5. The polymer blend of claim 2wherein said fraction insoluble in xylene comprises at least 20% byweight of said continuous phase.
 6. The polymer blend of claim 1 whereinsaid dispersed phase comprises particles of said thermoplastic firstpolymer having an average particle size less than 10 microns.
 7. Thepolymer blend of claim 1 wherein said dispersed phase comprisesparticles of said thermoplastic first polymer having an average particlesize less than 5 microns.
 8. The polymer blend of claim 1 wherein saiddispersed phase comprises less than 50% by weight of the totalheterogeneous polymer blend.
 9. The polymer blend of claim 1 whereinsaid dispersed phase comprises less than 30% by weight of the totalheterogeneous polymer blend.
 10. The polymer blend of claim 1 whereinsaid thermoplastic first polymer is a homopolymer of a C₂ to C₂₀ olefin.11. The polymer blend of claim 1 wherein said thermoplastic firstpolymer is a copolymer of a C₂ to C₂₀ olefin with less than 15% byweight of at least one comonomer.
 12. The polymer blend of claim 1wherein said thermoplastic first polymer comprises a polymer ofpropylene.
 13. The polymer blend of claim 1 wherein the second polymeris produced from a plurality of comonomers comprising at least one C₃ toC₂₀ olefin and at least one polyene.
 14. The polymer blend of claim 12wherein said at least one polyene has at least two polymerizableunsaturated groups.
 15. The polymer blend of claim 12 wherein saidplurality of comonomers comprise propylene and ethylene.
 16. The polymerblend of claim 1 wherein the blend is substantially free of processingoil and curative.
 17. The polymer blend of claim 1 wherein saidcontinuous phase comprises a curative such that no more than about 50%by weight of the second polymer is extractable in cyclohexane at 23° C.18. The polymer blend of claim 16 wherein said curative is selected froma phenolic resin, a peroxide and a silicon-containing curative.
 19. Thepolymer blend of claim 1 and further including one or more additivesselected from fillers, extenders, plasticizers, antioxidants,stabilizers, oils, lubricants, and additional polymers.
 20. A processfor producing a heterogeneous polymer blend comprising (a) a dispersedphase comprising a thermoplastic first polymer that is at leastpartially crystalline; and (b) a continuous phase comprising a secondpolymer different from the first polymer, the second polymer having acrystallinity less than that of the first polymer and being at leastpartially cross-linked, the process comprising: (i) polymerizing atleast one first monomer to produce the thermoplastic first polymer; (ii)contacting at least part of said first polymer with at least one secondmonomer and at least one polyene under conditions sufficient topolymerize said second monomer to produce, and simultaneouslycross-link, said second polymer as finely divided particles.
 21. Theprocess of claim 19 wherein said polymerizing (i) is conducted in thepresence of a catalyst and said contacting (ii) is conducted in thepresence of the same catalyst.
 22. The process of claim 19 wherein saidpolymerizing (i) is conducted in the presence of a first catalyst andsaid contacting (ii) is conducted in the presence of a second catalystdifferent from the first catalyst.
 23. The process of claim 19 wherein,following said contacting (ii), at least 5 wt % of said second polymeris insoluble in xylene.
 24. The process of claim 22 wherein the productof said contacting (ii) is subjected to an additional curing step tofurther cross-link said second polymer.
 25. The process of claim 23wherein, following said curing step, at least 70 wt % of said secondpolymer is insoluble in xylene.
 26. The process of claim 23 wherein saidcuring step comprises dynamic vulcanization.
 27. A process for producinga heterogeneous polymer blend, the process comprising: (a) selecting acatalyst capable of polymerizing a C₂ to C₂₀ olefin to produce a firstpolymer having at least 30% crystallinity; (b) contacting said catalystwith one or more C₂ to C₂₀ olefins at a temperature of at least 50° C.to produce a first polymer having at least 30% crystallinity; (c)contacting said first polymer and said catalyst with at least one C₃ toC₂₀ olefin and at least one polyene under conditions sufficient topolymerize said at least one C₃ to C₂₀ olefin to produce, andsimultaneously cross-link, a second polymer, whereby the product of saidcontacting (c) is a heterogeneous polymer blend comprising a dispersedphase of the first polymer having at least 30% crystallinity and acontinuous phase of said second polymer, wherein said second polymer isat least partially cross-linked and comprises at least 15 wt % of saidC₃ to C₂₀ olefin and at least 0.0001 wt % of said polyene.
 28. Theprocess of claim 26 wherein the first polymer produced in saidcontacting (b) has at least 0.01% terminal unsaturation.
 29. The processof claim 26 wherein said C₂ to C₂₀ olefin comprises propylene.
 30. Theprocess of claim 26 wherein said first polymer is contacted withethylene together with said at least one C₃ to C₂₀ olefin and said atleast one polyene in said contacting (c).
 31. The process of claim 26wherein said polyene has at least two polymerizable unsaturated groups.32. The process of claim 26 wherein the product of said contacting (c)is subjected to an additional curing step to further cross-link saidsecond polymer.
 33. The process of claim 31 wherein said curing stepcomprises dynamic vulcanization.
 34. A process for producing aheterogeneous polymer blend, the process comprising: (a) selecting acatalyst capable of polymerizing a C₂ to C₂₀ olefin to produce a firstpolymer having at least 30% crystallinity; (b) contacting said catalystwith one or more C₂ to C₂₀ olefins at a temperature of at least 50° C.to produce a first polymer having at least 30% crystallinity; (c)contacting said first polymer together with at least one C₃ to C₂₀olefin and at least one polyene with a catalyst capable of polymerizingbulky monomers under conditions sufficient to polymerize said at leastone C₃ to C₂₀ olefin to produce, and simultaneously cross-link, a secondpolymer, whereby the product of said contacting (c) is a heterogeneouspolymer blend comprising a dispersed phase of the first polymer havingat least 30% crystallinity and a continuous phase of said secondpolymer, wherein said second polymer is at least partially cross-linkedand comprises at least 15 wt % of said C₃ to C₂₀ olefin and at least0.0001 wt % of said polyene.
 35. The process of claim 33 wherein thefirst polymer produced in said contacting (b) has at least 0.01%terminal unsaturation.
 36. The process of claim 33 wherein said C₂ toC₂₀ olefin comprises propylene.
 37. The process of claim 33 wherein saidfirst polymer is contacted with ethylene together with said at least oneC₃ to C₂₀ olefin and said at least one polyene in said contacting (c).38. The process of claim 33 wherein said polyene has at least twopolymerizable unsaturated groups.
 39. The process of claim 33 whereinthe catalyst selected in (a) is different from the catalyst employed insaid contacting (c).
 40. The process of claim 33 wherein the product ofsaid contacting (c) is subjected to an additional curing step to furthercross-link said second polymer.
 41. The process of claim 39 wherein saidcuring step comprises dynamic vulcanization.